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Guppy Labs e-Bulletin

July 24, 2004

Guppy Labs e-Bulletin

Issue # 3


Sergio Chaim
Sergio Chaim,
Chief Editor

Enrique Patiño
Enrique Patiño,
Editor and
Webmaster
  


Welcome to our third issue of Guppy Labs e-Bulletin dedicated to the guppy, Poecilia reticulata. If you share our passion for this wonderful fish species on earth, this is also your bulletin. Our goal is to provide you with up-to-date information about guppy breeding and care.

This e-bulletin regularly include articles with information about guppy husbandry, guppy nutrition, guppy genetics, guppy diseases and health management, guppy Immunology, fishroom design and maintenance, guppy judging standards, international guppy news, and more. Please feel free to distribute it amongst your friends or people you know. We hope that you will find the content of this bulletin simple, complete, interesting and worthwhile reading.

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Guppy Labs Archives - click here

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IN THIS ISSUE

 
Dedicated To The International Community Of Guppy Enthusiasts

Authors In This Issue Are From:
Singapore
Taiwan
Brazil
Uruguay
Japan
El Salvador
-EDITORS' COLUMN

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Our Third Issue

We are absolutely delighted to continue to count with the support of writers from different parts of the world, whose articles make this e-bulletin worth reading. After all, this is an international bulletin. Bruce's article on some of Taiwan's guppy secrets takes us deep into Taiwan's guppy underculture. It is interesting that Bruce's article on Taiwan, and Tomoko Young's article on Japan, both elude to the emergence of regional methods for raising guppies. We are honored to be able to present these articles in our e-bulletin. We think that the Internet can expose some of these deeply rooted local traditions, or secrets to the rest of the world and that the benefits can be significant. We were able to see some differences and similarities in their respective approach, and were perhaps a little surprised at both.

Chris' article about the GCS is exactly the kind of article we hope to publish about international guppy news. Did you see who the judges were for their guppy competition? Tomoko's article about shipping guppies should be of interest to all of us. After all, what would be of the hobby without being able to distribute guppies around the planet? Sergio's article on biological filters for water recirculating systems provide tons of technical information as well as practical examples with guppies. It is work in progress for those of us interested in this subject. And Enrique's article reviewing studies about the inheritance of growth in guppies should also be of practical value to us in our fishrooms. We have introduced a new Short Communications column in the bulletin, where we will present short articles under one column. In this issue, we are also including abstracts from three recent scientific publications on guppies.

So, what is next? We are very happy with the results so far, and are hopeful and excited to continue with the current format into the future. We will continue to work with writers using the current format. Also, at some points or intervals, we may consider releasing special issues in subjects such as: Guppy genetics, guppy nutrition, guppy immunology and health management, systems design, etc. Our first special issue will be about guppy genetics and should come out on or before January 2005.

Due to storage limitations, we can only have two issues on our server. Earlier issues are always available in .pdf format upon request. To request an earlier issue not on our server click here.

Enjoy reading and please e-mail this e-bulletin to guppy-people you know.

-The Spotlight:   By Chris Ng

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Singapore

Guppy Scene Of The Lion City

There is a steady interest in the guppy in Singapore. Apart from being known as one of the world’s largest producers of fancy guppies, in the 1970s there were also many awards from active participation in international shows.

Guppy farms in Singapore are consistently improving their stock and creating new varieties or strains, such as Japan-blue blue diamond. Individuals growers had imported fancy guppy strains from overseas and developed their own...


Young Japan blue blue diamond male and purple tail male

Guppy Club

The Singapore Guppy Club was formed in the late 1960s, which actively promoted the appreciation of guppies through fairs and other events. Crowds gathered wherever there were any guppy shows. But due to the shift of focus to commercial production, the public attitude towards fancy guppies in Singapore became less positiveE/FONT>

The millennium brought good news. Via the Internet, more Singaporeans became more aware of fancy guppies and better informed, and people began viewing guppies in a more positive light. Guppy enthusiasts started getting together again and continued discussing more about the fish they loved. Over time, The Guppy Club (Singapore) was revived.

The Guppy Club (Singapore) http://www.sgguppy.com/ (GCS) was officially registered on 14th Feb 2004, and a series of activities were planned to further create awareness about fancy guppies.

Singapore Guppy Open House

The first open house was held on 10th April 2004 at a member’s home. Response was great!  Guppy enthusiasts gathered to meet up with each other and also register themselves as members of the club. A talk on red guppies and an auction allowed members to know more about their fishes and acquired new guppies.

First Singapore Guppy Competition

The 1st GCS National Guppy Competition was held on the 29th May to 2nd June 2004 at the Bukit Timah Plaza. There were 96 entries in the 6 classes available.


100 tank setup

GCS booth


Some fishes in the show

Six classes

a. Solid Single Colour / Plain tail

b. Tuxedo (Half/Blacks).

c. Mosaic - all colours.

d. Grass - all colours.

e. Snakeskin/Cobra

f. AOC - all colours

g. New Strains/Open

Judging criteria:         

 Focus Areas Standards               Overall allocation of points:

a. Length of fish                            1. Body E25%

b. Shape of fish                            2. Dorsal E25%

c. Pattern of fish                          3. Tail E50%

d. Colour of fish                          4. Overall E100% (Additional points/penalties included)

This was a major event organized by the GCS, and we consider it a success. Crowds gathered to view the competing (matched pair) male guppies, which delighted the adults and children with their beautiful finnage.

At the GCS booth, there were sales of fancy guppies such as ribbon blue grass, albino galaxy, etc., at affordable prices. That coupled with lots of freebies, stimulated lots of interest in guppy keeping. The GCS members are spotted mingling around the show area, readily sharing experiences and knowledge with the members of the public. Some guppy enthusiasts who had kept a low profile also came to the show, where they shared their guppy experiences with others.

The judges for this GCS National Guppy Competition were Professor Violet Phang, renowned guppy researcher, Ms. Pauline Teo, Director of Teo Way Yong & Sons Pte. Ltd. and Mr. Richard Woon, President of the former guppy club. The judges have extensive knowledge about guppies, which greatly benefited the participants as they pointed out the merits and demerits of certain fishes and the entries in general.

This has been a good start for the Guppy Club and I believe that the hobby will reach greater heights in Singapore.

 

-Raising Guppies in Taiwan: By Bruce Hsueh

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Taiwan

A Popular Automated Water Changing System

There are many reasons why we breed guppies; enjoy their beauty and company, see through the cycle of life, make our own strains, meet new friends, win shows, and some make extra income. The list can go on and on. But like everything else, there is always the down side. Among the top of the list, and certainly in my case, has to be the time spent for the water change. You know this is true if you own around 50 tanks like me. And I can certainly feel your pain and suffering if you have more than 100 tanks. For breeders who own more than 200+ tanks and have to change water by the old fashion way of siphoning and hosing water in from a nozzle, I truly sympathize for you.

Time is money! For those of you who aren’t old enough and some, like me, who are almost old enough but just plain too broke to retire, we know this is also true. Here is a popular automated water changing system adopted by most of the large scale breeders in Taiwan, which will facilitate breeders like me and alleviate some of the burden of changing water for the large scale breeders.

My friend, Lin Sheng-Hwei, who befitted about 72 36-liter (about 7.5 gallons) tanks with this system and the total amount of time he spends to change 80% of water for all 72 tanks is about 25 minutes. That’s over 400 gallons of water change in 25 minutes!

We all had some bad experiences with the overflow of water; a phone rang or someone called you away while filling up the tanks, or in my case, getting old and forgetful. But with this system, there is absolutely no chance for overflow.

Here is the basic set up:

2 EGlass partition for the gravel and undergravel filter.

4 EUndergravel filter with legs which raise the filter about one inch off the bottom (purple)

6 EPartitioned area for the gravel and sized perfectly to fit the filter.

8 EWater outlet (flanged and O-ringed to prevent leaks)

9 EOutlet piping, approximately 1-inch inner diameter plastic piping (red)

10 EFlow valve (green)

12 EInlet piping, same size piping as outlet (actually L-shaped and not slanted like in the diagram) (blue)

14 EWater inlet valve, same size piping as outlet (green)

16 EOverflow outlet, approximately 1/2 to 5/8-inch inner diameter

18 EOverflow piping (orange)

20 EUnder-gravel filter outlet (inverted L-shaped at the top)

30 EPartitioned tanks(or in Lin’s set up, individual tanks)

This is how the undergravel filter looks like

Here’s a photo of a multi-tank set up:

I personally think this masterpiece of design was the result from someone’s or collective experiences from many breeders. As of this moment, I still don’t know who had originally come up with this design. But here are some of the principles behind this system:

1.          Overflow outlet prevents any water flow unto the floor while adding water to your tank.

2.          Self-cleaning. First thing that gets sucked out is the accumulated excrement in the gravel.

3.          Inverted L-shape blasts any excrement in the front to the back.

Here are some more details to this design which were not in the diagrams:

1.        Plastic “air distributorsEinstead of air stones are used for all under-gravel filters. Air stones get clogged easily and require extremely large amount of air power, and hence, shorten the life of an expensive air pump.

2.        Overflow outlet sticks out slightly and capped by a net material to prevent any fish who wants to take an adventurous ride down to the sewage system. (Not capped in Lin’s system.)

3.        Large sized gravels, 1/8 to 1/4 in diameter, which harbor lots helpful bacteria, serve the best in this system (size really depends on the thickness, or amount, of the gravel and the flow speed through the gravel). To have an affective undergravel filtering system, the ability to harbor helpful bacteria by the gravels is probably the most important factor.

4.        The overall speed to change a certain amount of tanks in this system really depends on the inlet water flow rate. If you want speed, installing a water pump at the inlet water supply is highly recommended.

5.        Air piping not showing. See picture

6.        Inlet piping is capped and a small hole drilled in the middle to create a funnel or an orifice to control the flow.

7.        Air stones can be opened and cleaned. Life time usage!

After chatting with Lin, here’s one suggestion he made to improve this system. The partition which boxes in the gravels can be lower than what he has now. He sometimes has the problem of clogging due to the large amount of gravels. To solve the clogging problem, he has to poke or stir up the gravels with a stick while draining the water. He thinks about half the amount of gravels will accomplish the same task.

The initial set up for this system could cost money and require man power. It takes lots of piping, flanges, L-connectors, T-connectors, and custom-made tanks with two predrilled holes in each. All Lin’s tanks are tempered, so the holes have to be cut before they are annealed. Like everything else in business, the cost can be calculated and the hours required to install this system estimated. Then you can evaluate and ask yourself if this is a good investment for your fish room and your future.

 

-Raising Guppies In Japan:  By Tomoko Young

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Japan

Since I have been in guppy breeding in United States, I can't even remember how many times people have asked me why majority of Japanese breeders can be successful breeding guppies using undergravel filter and small tanks. And my answer to the question has always been enough to satisfy the people who asked me.

Guppy is the famous well known fish who has very delicate caudal, and that's one of the biggest reason for failure using this filtere, specially among show breeders in United States. The poor chemistry often destroy the delta caudal which is the trademark of American show guppy. Some known breeders believe that undergravel filter cannot support the heavy feeding which is required for raising the large size guppy. As the most common result, people give up to use it within few month before the good bacteria start to grow on the surface of gravel.

Anyway I try to introduce today how Japanese have received the benefit by using undergravel filter systems, and how we overcome the common problem and got success to establish our unique regional breeding style as the whole country's official setting.

Also many thanks to both Enrique and Sergio for language support. I couldn't finish this article without their encouragement.

These pictures are from Mr.Shinichi Kobayashi, who is the owner of Studio Poecilia, in Suwa City, Nagano, Japan. Studio Poecilia is a famous guppy shop around the world through Internet for his creativity. Mr. Kobayashi is very successful to use both undergravel filter and plants for part of the 600 tanks in his shop. His growing methods basically rely on the natural biological power of gravel & plants.

 

When I visited Studio Poecilia couple years ago, I was really thrilled to see how one person could take care of so many tanks without any recirculating system or or assistant employees. All he got was the classical Japanese setting with river sand which is called " Oiso ", and just so many quantities of small tanks for cross experimentations. It was absolutely stunning.

Some of the water he uses for breedingis is slightly green in color. All the fish are healthy and lively, especially fries look happy in that water. He tells me that all the things he does are in purpose, by his faith and confidence from his own long experience of actual breeding, not just from the knowledge of books.

He says his basic daily maintenance is changing water once a week, and it's good enough for his fishroom. Also he mentions that he is occasionally clean the whole tanks as well as other Japanese breeders do, and this work cause a lots of task for him. What this work is called in Japanese word " Maru - Arai " is the biggest pain job for breeders. In order to decrease the amount of this hard work, some breeders are using liquid bio bacteria extract . And seems it works for protecting male caudal too.

If any of you have chance to go visit to Japan, try get out from Tokyo sometimes with local train for seeing Mr. Kobayashi & his guppies. His place Suwa is located deep inside of central Japan which was the capital of the ancient Japanese culture. I guarantee you will discover special treasures there...! These are some of Mr. Kobayashi's guppies.

 

From Hawaii

This are parts of my fishroom. Slightly dirty with green algae...It has been 3 years since established. Have never bleach any of tanks and filters yet. In the first year, there were disease attack couple times , but after that less troubles month by month. And now finally no problem with real heavy feeding - average 5 times a day.

I normally change 80% of the water once a week, but basically want to escape from this job as much as possible. I sometimes dump a capful of liquid vitamins into each tank. Or constantly mixed with baby brine shrimp when I feed to guppy, so the tank water can stay O.K. for 2 weeks maximum.

In fact there are various different settings in my guppy room and I try to compare how the results are in each setting - undergravel filter, sponge filter, corner box filter, outside power filter, plants with plain bare tank without any filtering and also a water recirculating system which I'm learning from my husband who has been in saltwater aquarium fish industry for 35 years. See above pictures which protein skimmer & bioball tower I rely on. And the fact that the professional water recirculating system gives the best result and needs much less maintenance.

However I would like to say here that undergravel filter is also almost good like a system once it works - even it's the oldest and the most classic method. One very known marine aquarium fish breeder in University of Hawaii has been adopting undergravel filter with coral sand for breeding his Centropyge angelfishes since a while ago. And he is also wondering that the percentage of survival of fries are much higher than using his expensive recirculating system.

Maybe we need more research for a while about this subject ...

These are some of my guppies...

 

-Shipping Guppies: By Tomoko Young

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Uruguay

Adopting saltwater fish packing techniques for shipping guppies

I would like to share a little different way to pack guppy which I learnt via my family who is a long time experienced exporter of saltwater aquarium fish. Since I have switched to this method from standard guppy packing, Seems like guppy last longer and healthier, also less percentage of accidental DOA during the long distance transportation.

These are the stuffs I'm using for actual shipping and it's quite simple !

(1) Thick & double 5" shipping bag with new papers.

Newspaper is for fish to be relax and calm down. Also if the water leak from the shipping bag during transportation, newspaper take care of it. Using thick nylon shipping bags is for protecting fish from bag breaking by air expansion on the airplane.

(2) High density styro foam box


(3) Heating pack ( only during winter season ) or ice pack (only during the hottest season)

(4) Shipping water with a mild antibiotic (nitro furazone) or bag buddies

Try give the priority of fish health and survival than saving $ 5 to $10 shipping cost. Use extra amount of water instead of too little water. If the shipping cost become overprice than your pocket money, then maybe have to throw some water.


(5) Oxygen

Always use it. Never forget . Actually guppy can ship without oxygen but the risk is high and you would notice that guppy were often gaping for suffering from oxygen starvation in the shipping bag , or either would die within 1 week after acclimate.


(6) Clipper

This is typical saltwater fish packing material. Works great for fresh water fish packing too.


See how simple it is. Here is also pictures of mass packing...

 

 

-Sizing Biofilters: By Sergio Chaim

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Brazil

Sizing a Trickling Biofilter:

Part I EEstimating Waste Production and Oxygen Demand.

In my last article I went into something that I intended could be helpful for both, the too lazy and the too busy guppy breeder. Here I shall deal with harder subject. In this article I will go deeply into our more secret dream or wish, to get rid the boring paleosoic hose and bucket system and build a water recycling system.

We have two options in order to decrease the concentration of  harmful compounds in the aquarium water: (1) change the water or (2) recycle the water. Although you might be able to get rid the hose and bucket simply using an automated water change system, I sincerely think that soon or later, all among us will shift to recycle. Do not think I’m another green". Surely I am not. I am just concerned about the most sensitive part of my person, my pocket... You could say  that recirculating systems don't work for guppies. OK, perhaps you’re right, but the same was said about artificial feeds. A few decades ago it was impossible to reproduce and to grow fish feeding them only on artificial feeds. Right now, at least for the most important commercially cultured species, is possible to produce fish, generation after generation, only on artificial feeds. Do you know what makes that possible? The experience, the background, the practice. I just think its the same with water recycle systems. As soon as we begin to use them, the sooner we will know how use them. But for those still skeptical about this subject, I hope that the data presented here help you understand better design concepts and build a more rational water management system.

For an introduction to the topic of biofiltration, I suggest you take a look in the documents available at Aquanic site. Reading the series of web pages on that site is a great way to immerse yourself in the topic in general. What I try to do here is to make this subject relevant for guppies and other important ornamental species.

This article is based in a spreadsheet I developed to size a trickling biofilter for my fishroom. My spreadsheet is similar to the spreadsheet developed by Losordo and Hobbs (2000) to size biofilters for food fish raising plants.

Since almost there is no data about designing recycle systems for guppies or tropical ornamental fishes I am joining pieces of information from many different sources. I was intended to cheat Murphy’s law. But to write about all the infromation available in only one article proved to be impossible, so I spread these information in two pieces. For now we are publishing Part I, related to estimating waste production and oxygen consumption. Part II, which deals with sizing the biofilter sizing itself, will be published in our next issue.

Colt (1986) proposed a “Mass Balance Approach”  for the design and operation of fish culture systems. “  This method is based on identification of the critical environmental parameters that may limit the growth of fish. These may include, dissolved oxygen, carbon dioxide, ammonia, and solids. Based on laboratory and production experiments, a water quality criterion is set for each parameter. Then the water flow required to maintain each parameter is computed for the specific hatchery conditions.E/font>

I chose a trickling biofilter because I can mange at least three of the four critical environmental parameters. Trickling biofilters remove ammonia, add oxygen to the water and can provide some carbon dioxide stripping with relatively low costs for start up and operation. 

We know that the amount of metabolism byproducts released by fish into the system is proportional to the amount of feed consumed (Haskell 1995), cited by Ng et al. (1983)  Our first step is to estimate the amount of feed released into the system. We can do that by entering data on the system configuration, its management, and the fish biomass and daily feed allowance can be estimated. The second step is to estimate the amount of metabolites produced by guppies fed this specific amount of feed. There are different methods found in literature which are suitable to estimate total ammonia nitrogen (TAN) production (indeed size the biofilter), total suspended solids (TSS) production (indeed size a solids removal device) and nitrate production (indeed estimate the need of the system for new water), among others metabolites. The third step is to estimate the amount of oxygen consumed by the fishes, by the water biochemistry and by the biofilter through the nitrification process. 

The Spreadsheet

If you want a copy of the spreadsheet, e-mail me.

1 ESystem and Management Related Parameters.

1.1 ETotal Volume of Water

 This is the total volume of water held by all tanks connected to the filtering unit being sized, it is expressed as liters (l).

The rack at my fishroom is divided in 3 levels. In the upper board I have eighteen 20l aquaria used to house breeding trios, females about to delivery and young frys. At the middle and lower boards there are fourteen 40l aquaria per level used to house breeding groups, older frys and growing sexed fishes. This arrangement is compatible with the thermostats we have available in Brazil and when associated with heaters of  different power it had allowed me, until now, have some age specific temperature control.  Due sanitary reasons and because if I wanted recycle all this water in only one filter  I would need much more energy for pumping the water through the whole height of my rack I decided to set one filter per board.

Then a filtering unit for the middle or lower rows of my rack should handle 14 X 40l and I should type E60Eor E14*40Eas answer but without the quotation marks. Let’s say you want size a filter for a system with different tanks, let’s say you have eight 20l, twenty 40l and five 60l aquaria, so you would type E(8*20)+(20*40)+(5*60)E

This is the mass of the largest fish will be raised in the tanks connected to the filtering unit being sized, it is expressed as grams of body weight (g bw).

Usually we take management related decisions based on fish age instead fish weight. To know the mass of the guppies at different ages we should know their growth curves. Because I have not an analytical scale I had to figure some estimates on the growth curve of  fancy guppies. The basic data for this guessing exercise was taken from Shim and Bajrai (1982).  I worked on their data basically because: (1)  they used a raising method somewhat similar to the one we practice (segregated sexes, 12 fishes in 33l of water, once a week 1/3 water change, 1ppt of salt in the water, aeration, pH 7-7.7, temperature 27-28ºC, once a day feeding in “all you can eatEstyle); (2) there were treatments were they fed the fishes on tubifex that is recognized as a great feed for growing guppies, but they also used Aquavite, an artificial food, that surprisingly supported the same growth rate as tubifex during experimental period; and (3) they used a strain of fancy guppies as test animals. This study only covered the exponential growth phase (5 to 20 weeks old fishes) so I estimated the subsequent growth until their growth curves reached a plateau characteristic of  the expected sigmoidal shaped curve. I did so estimating the evolution of their percentile weight gain and calculating the expect body weights for ages subsequent to the finish of experimental period. This plateau I make reference is not exactly a zero growth state like represented in the graphics but a state were percentual weight gain approach zero but fish yet keep growing.

Figure 2 EGrowth Curve of Female Guppies Fed Tubifex or Aquavite Artificial Feed. Adapted from Shim and Bajrai (1982).

Figure 3 EGrowth Curve of Male Guppies Fed Tubifex or Aquavite Artificial Feed. Adapted from Shim and Bajrai (1982).

 Also like most among us simply don’t have access to analytical scales but to rules I planned to create a mathematical model to express lenght-weight relationship for guppies of different sexes. Unfortunately I had no access to a reliable and significant data set which allowed me to properly calculate this model. But using a limited data set covering 31 means for females and  15 means for males of fancy guppies strains and  the spreadsheet software tendency projection tool it was estimated the equations and curves in figures 4 and 5. Since their R² values are quite high I’m comfortable to use these suppositions.

Figure 4 ELength–Weight Relationship for Female Guppies. Adapted from Several Sources.

Figure 5 ELength–Weight Relationship for Male Guppies. Adapted from Several Sources.

 Perhaps you yet know that all these above are some kind of fake science but it is the best I could to do considering the complete lacking of data covering fancy guppies.

Itzkovich (2002) stated that guppies raised in Israel reach market size (3.5-4cm) at 2.5-3 months age. From figure 2 we see that a 2.5 months old (or ~77 days old) female guppy should weight 0.280g if fed tubifex or 0.315g if fed Aquavite; and a 3 months old (or ~91 days old) female guppy should weight 0.360g if fed tubifex or 0.415g if fed Aquavite. From figure 4 we see that for these body weights they should measure 30mm. 31mm, 32mm and 34mm, respectively. Inversely, by these models females guppies should reach 35mm and 0.465g when 98 days old if fed Aquavite and when 105 days old if fed tubifex, and 40mm and 0.700g when 135 days old if fed tubifex. Theoretically females fed Aquavite should never reach 40mm and/or 0.700g.  May be these models need some refinement.. If you have any data or idea to improve this model I’ll be glad to hear you.

Well, back to example of my fishroom. Like I said the middle and lower boards of my rack are for growing fishes and breeding groups, so the heavier fish I expect house there are breeding females around 2g.

 1.2E Maximum Stocking Rate.

 This is the maximum number of fishes expected to be raised per unit of water volume, it is expressed as fishes per liter (fishes/l). Al thought most authors make reference to the number of fishes stocked per unit of water volume as stocking density I personally think that “density”  is somewhat  more related to a relationship between weight and volume (gram per liter or kilo per cubic meter), so when possible I make reference to the relationship between the number of individuals and volume of water as stocking rate.

Kaiser & Vine (no date) investigated the effect of  stocking rate on growth, fin development and survival rates of juvenile fancy guppies in a closed recirculating system. They used 21x29x23cm aquaria holding 12l of water at an exchange rate of 3 exchanges per hour, 16h light and 8h dark light regimen and temperature set at 24°C. The fishes were fed 2 times a day  on commercial flaked diet slightly in excess of what they could consume within 20 minutes and uneaten food was siphoned once daily. The treatments were stocking rates of 1,3,6 or 12 fishes/l.

Figure 6 - The Measurement of Body and Fin Dimensions in Male Guppies. From Kaiser & Vine (no date).

 These authors found that different stocking rates did not have any effect on the weight gain and on the growth in standard length of male guppies. In average male guppies gained 2.54± 0.31mm and 0.14g per fish after 11 weeks. But total length gain differed significantly between treatments where fishes at lowest stocking rate grew 0.12mm/day, while there was no difference between the other 3 treatments, which averaged 0.09±0.01mm/day, suggesting a better fin growth at the lowest stocking rate. Also male guppies developed their caudal fins faster at the lowest stocking rate, while there were no differences between the other 3 stocking rates. At the end of the study the ratio of caudal fin height to standard length averaged 0.74±0.029, 0.67±0.24, 0.64±0.029 and 0.63±0.026 at 1,3,6 and 12 fishes/l, respectively.

Citing Kaiser & Vine (no date)  “In female guppies the effect of stocking rate on growth was more pronounced than for males. The significantly highest growth in gain was recorded for the lowest stocking density (p<0.01), the second highest for a stocking density of three fishes per liter (p<0.05), while there were no more differences between the two other densities. Standard length and total length dev elopement were highest at a stocking density of 1fish/l but did not differ between the other 3 treatments.ESurvival rates were not significantly different between treatments and exceeded 75% at all stocking rates. 

Itzkovich (2002) described how guppies are cultured Israel using tanks provided with pre-maturated internal filters, just like our box filters and technically called upflow submerged filter, corresponding to 10% of tank volume, which are filled with plastic media and with 5-10% daily new water change. He reported stocking rates of  2.000-4.000 frys (1 to 30 days old) per 500l, 10.000-30.000 male or female growing fishes (31 to 90 days old) per 20m³ and 300 breeders (250 females + 50 males) per 500l. This author also stated that these guppies reach market size (3.5-4cm) at 2.5-3 months age.

Fernando & Phang (1985) when describing how guppies were cultured in Singapore reported that they were raised in cement tanks without aeration  but with about two-thirds of the water in the tanks being siphoned out an replaced every 1-3 days at stocking rates of  140-300 frys/m³ (1 to 17-21 days old), 160-320 growing males/m³ (22 days to 3-4 months old), 100-200 growing males/m³ (4 to 6 months old)  and 115-180 breeders/m³. These authors didn’t made any comment about it but I saw a tendency of  larger tanks  to support more fishes per cubic meter of water than smaller ones.

IFGA recommends aeration/filtration, 20-40% water changes per week and  twenty to twenty five guppies per ten gallons (fish that are 5-7 months).

Taking the data from Itzkovich (2002) who reports the highest stocking rates breeding females would need from 1.66 liters per fish (if I take males into account, 250 females+50 males per 500l) to 2 liter per fish (if I don't take males into account because they are relatively smaller than females, 250 females per 500l). The same author also states that 30.000 growing fishes could be housed in  20m³ or 1.5 fishes/l. All said I assumed a possible stocking rate of 1 fish/l. This do not mean I’ll use this stocking density but only my filter will be able to manage the waste produced at this stocking rate.

1.3E Maximum Feeding Rate.

This is the maximum amount of food dry weight a fish will be fed, it is expressed as percentage of body weight (% bw).

Feeding rates usually do not fit well when calculated based in feed weight as it does when calculated based in feed dry weight Shim and Bajrai (1982). It is much more significant for those who use feeds which huge differences in water content like artificial/live/frozen feeds and pastes. So I suggest you enter/understand feeding rates in dry matter basis, at least for feeds that are moisture rich. Table 1 show the proximate dry matter of common guppy feeds.    

Shim and Bajrai (1982)  wrote about it about guppies that were 5 weeks old in the beginning of their experiment and were raised up to they reached 20 weeks age EThe fish were fed once daily. The amount of food given was initially about 10 percent of the body weight. In cases were the dry matter is very low like in Moina, for example, the amount given was raised such that the dry matter on which they were fed would be about equivalent to the amount of dry matter for the other food types. However with experience, it was found that the constant percentage rates far exceeded the appetite of the fish. Lower amounts of food had to be given to prevent food wastage as well as to get a more accurate measurement of the od food consumed.E

Itzkovich (2002) reported feeding rates about 5% of the total biomass daily.

Usually warm-water food fishes at early life stages, if kept under optimal temperatures, are fed 10-30% body weight, at later growth stages the feed allowance is reduced to 3-10% body weigh until maturation and it reaches 1-3% body weight for brood fish. So I assumed a conservative 10% body weight daily feeding for breeding females.  

1.4 EDiet Crude Protein Content.

This is the relative amount of protein contained in the whole diet served to the fishes, it is expressed as percentage of feed (% feed).

When I say whole diet I mean take into account the proportion between the different feeds you fed to your fishes and their individual crude protein content.

Ebeling (no date) mentioned that in the aquaculture environment there are four primary sources of nitrogenous wastes; (1) urea, uric acid and amino acid excreted by the fishes; (2) organic debris from dead and dying organisms, (3) uneaten feed and feces and (4) nitrogen gas from atmosphere. We know that among these four sources of nitrogen the two most important for us are #1 and #3 and they correlated to the feeding. Also we know that the nitrogen content of the food is closely related to its protein content. He  also states that “A general rule of thumb is that about 3% of daily feed ends up as ammonia-nitrogen in the water, Al thought this is also a direct function of the protein level in the feed.E Actually when you read the label in a feed package and you see  that it has 40-50% crude protein, you are not really buying a fed having 40-50% amino acids that is which truly made up proteins, but you are buying something that was analyzed, or something made up by ingredients which were invidually analysed, for its/their nitrogen content and this nitrogen content was multiplied by a constant (6.25) based on the assumption that proteins contains 16% nitrogen (NRC, 1993). Then at least na article, Losordo and Hobbs (2000) estimated TAN based in this fact.

I strongly recommend you standardize this data as percentage of dry weight, instead percentage of feed, because experimental diets usualy average 90% dry matter like most artificial feeds. Also Follow a table where you can see the proximate analysis of some few ingredients and feed commonly used for guppies. 

Table 1 EProximate Moisture and Crude Protein Contents of Common Guppy Feeds. From Several Sources

Feed

Moisture

Crude Protein

Crude Protein

% Feed

% Dry Matter

% Feed

Moina

96,5

70,00

2,45

Bloodwoorm

90,7

62,60

5,82

Tubifex

83,2

71,20

11,96

Aquavite

10,7

52,90

47,24

Gelatin

13

85,60

Beef Heart

75,56

17,50

Spirulina

4,68

57,47

Beef lier

68,99

20,00

Microworms

76

40

9,60

Dried Decapsulated Cysts*

10

50,60

45,54

Brine Preserved Decaps.Cysts - Drained 10' **

20

50,6

40,48

BBS*

90

56,20

5,62

Adult Artemia*

85

67,40

10,11

        * - Estimated Moisture Content.

        * - Estimated Moisture Content and Crude Protein.        

1.5E Fish Biomass.

This is the total amount in weight (mass) of fishes to be raised in the system being designed, it is expressed in grams of body weight (g bw).

Fish biomass was calculed multiplying the total volume of water by maximum fish weight by maximum stocking rate.

1.6E Daily Feeding Allowance.

This is the whole amount of feed expected you will input into your system daily, it is expressed as grams of feed per day (g/d).

Daily feeding rate was calculated multiplying fish biomass by  maximum feeding rate.

2 EEstimatives of Waste Production.

Several researchers had worked to generate data to suport the rational design of aquaculture systems, with or without reuse of water, but they had mostly worked with cold water salmonid species. We can cite Colt (1986) who stated that 1lb of feed fed to salmonids demande 0.20lb of oxygen and produce 0.30lb of ammonia, 0.30lb of fecal solids and 0.28lb of carbon dioxide.

Ng et al. (1983) were the only ones, as far as I know, that studied metabolite production rates of tropical ornamental fishes but sadly they didn’t included guppies in their study. Below is parked a table 2 which I adapated from the results of  their studies including some basic statistics. Their findings surprised me because I even took goldfish and koi as the greatest aquaria hogs but not poecilids at all. Poecilids holded all maximuns values for metabolites production. Perhaps it is related to same mechanisms that make a 1kg of small fishes consume more oxygen than 1kg of large fishes, it is something related to the increased metabolic rates in small living beings. Also Ng et al. (1983)   expressed the metabolic production as mg of metabolite per kg of fish per percent feed per day (mg metabile/kg fish/% feed/day) and since 1kg of fish fed 1% body weight daily will eat 10g I adapted their unit to mg of metabolite per g of feed (mg/g feed). 

Table 2 - Metabolite Production Rates of Various Ornamental Fishes (mg metabolite/g feed).

Adapted from Ng et al. (1983) .

Fish

Size(g)

Ammonia Nitrogen - Amm-N

Total Suspended Solids - TSS

Total Phosphate - TP

Total Kjedhal Nitrogen - TKN

Biochemical Oxygen Demand - BOD

Rosy Barb

1,33

15,59

32,50

3,41

24,93

34,00

 

1,67

12,95

 

3,67

21,27

 
 

1,68

14,50

97,50

 

22,79

52,00

 

2,08

14,27

 

3,02

18,45

 
 

2,29

13,20

24,40

2,21

21,07

82,90

 

3,84

11,96

 

2,56

18,77

 

Koi

1,27

17,51

113,30

 
 

74,40

 

5,10

12,84

97,40

 
 

62,50

 

25,70

9,83

113,20

 
 

81,70

 

31,68

13,60

121,70

 
 

71,40

Pseudotropheus auratus

3,86

13,30

 

2,55

21,44

40,70

 

7,03

 

168,60

 
 
 
 

11,23

13,35

 
 
 

30,90

 

11,48

 

233,50

 
 
 
 

18,45

 

134,60

 
 
 
 

23,82

12,30

 
 
 

40,40

 

55,17

 

168,60

 
 
 
 

73,67

 
 

2,52

19,41

58,50

Goldfish

5,50

13,26

111,10

1,28

20,02

70,50

 

9,00

14,13

108,10

1,70

20,44

42,60

 

43,80

13,27

167,00

1,00

17,18

66,50

 

175,50

6,88

143,80

1,13

13,37

43,40

Platy

0,53

 

259,40

1,22

20,08

103,80

 

1,02

15,86

170,00

 
 

55,80

 

1,55

 

276,00

 
 

56,80

Swordtail

0,73

16,41

165,20

1,65

20,99

61,50

 

0,93

17,67

236,50

2,64

30,37

70,90

 

1,83

 

174,60

4,10

 

125,50

Overall

Maximum

17,67

276,00

4,10

30,37

125,50

 

Minimum

6,88

24,40

1,00

13,37

30,90

 

Average

13,63

148,43

2,31

20,71

63,18

 

SD

2,47

65,81

0,97

3,73

22,98

 

n

20

21

15

15

21

Non-Poecilids

Maximum

17,51

233,50

3,67

24,93

82,90

 

Minimum

6,88

24,40

1,00

13,37

30,90

 

Average

13,10

122,35

2,28

19,93

56,83

 

SD

2,26

52,54

0,91

2,91

17,45

 

n

17

15

11

12

15

Poecilids

Maximum

17,67

276,00

4,10

30,37

125,50

 

Minimum

15,86

165,20

1,22

20,08

55,80

 

Average

16,65

213,62

2,40

23,81

79,05

 

SD

0,93

49,56

1,28

5,70

28,91

 

n

3

6

4

3

6

Since I personally think that the names of each estimated parameter under this topic is self-explanatory I’ll avoid to build silly definitions...

2.1 - Estimated TAN Production.

Several methods has been proposed to estimate TAN production. Since our main concern when using a biofilter is the TAN removal I propose to calculate TAN production by all methods and use the highest one for biofilter sizing and others estimatives.

2.1.1 ETAN Production - 3.5% Feed Rule.

Liao and Mayo (1974) and Wheaton et al. (1994), cited by Losordo and Hobbs (2000), in general observed that  2-3.5% of input feed by weight  becames TAN.

Colt (1986) stated that 1kg of feed produces 0.03kg of TAN, or 3%.

2.1.2 ETAN Production - 6.5% Crude Protein Rule.

Losordo and Hobbs (2000) estimated TAN production as 6.5% of the protein in diet.

2.1.3 ETAN Production by Ng et al. (1983)  - Maximum Data for Poecilids.

Ng et al. (1983)  were not pretty clear about what they called ammonia-nitrogen but I’ll assume they meant TAN. They obseved a maximum production of 17.67mg Amm-N/g feed or 1.767% Feed.

2.1.4 ETAN Production by Ng et al. (1983)  - Corrected Data for Poecilids.

 When you compare the maximum TAN produced by poecilids in Ng et al. (1983)  you’ll find that 1.767% of the feed becames TAN while for salmonids it is expected that 2-3.5% feed becames TAN. This can be explained by the low crude protein content of their experimental diet (24%) compared with at least 40% crude protein in the diet of salmonids. Actually we use diets of at least 50% crude protein. So I propose twice their initial estimative

2.2 EEstimated Nitrite Production.

I had adapted the stechiometry of nitrification from Ebeling (no date):

Equation 1 ENitrossomonas:

2 mole NH4 + 3 mole O2 => 2 mole NO2 + 4 mole H + 2 mole H2O + 84kcal / mole ammonia.    

Translation... 36g of ionized ammonia (or 28g of ammonia-nitrogen) is burned by 96g of oxygen producing 92g of nitrite (or 28g of nitrite-nitrogen) + 4g of hydrogen + 36g of water + energy.

Equation 2 ENitrobacter:

2 mole NO2 + 1 mole O2 => 2 mole NO3 + 17.8 kcal / mole nitrite.

Translation... 92g of nitrite (or 28g of nitrite-nitrogen) is burned by 32g of oxygen producing 124g of nitrate (or 28g of nitrate-nitrogen) + energy.

Equation 3 EOverall Nitrification:

2 mole NH4 + 4 mole O2 => 2 mole NO3  + 4 mole H + 2 mole H2O + energy.

Translation... 36g of ionized ammonia (or 28g of ammonia-nitrogen) is burned by 128g of oxygen producing 124g of nitrate (or 28g of nitrate-nitrogen) + 4g of hydrogen + 36g of water + energy

I hope I’m right since I didn’t loose any gram of nitrogen...

From the above relationships we see that 1g of ionized amonia produces ~2.56g of nitrite and/or ~3.45g of nitrate, and that 1g nitrite produces ~1.35g of nitrate. On ther hand when expressed as nitrogen base ammonia-nitrogen, nitrite-nitrogen and nitrate-nitrogen are kept always as 28g or 1:1:1 ratio.

.Since nitrite-nitrogen production in the system is expected to be equal TAN production I’ll express it in a different fashion. I’ll express it as nitrite itself. I propose estimate nitrite as 329% of TAN production (92g of nitrite / 28g of ammonia-nitrogen).

There is another data given by Ebeling (no date) that is not related to this topic but it is quite useful for management of recycle systems: 7.14g of alkalinity, as CaCO3 are needed for the comple oxidation of 1g of ammonia-nitrogen,  as rule of thumb 0.25lb of baking soda per pound of feed consumed should to be added into the system.

2.3 EEstimated Nitrate Production.

Like for nitrite-nitrogen, nitrate-nitrogen production in the system is expected to be equal TAN production. Then I’ll express it also nitrate itself. I propose estimate nitrate production as 443% of TAN production (124g of nitrate / 28 g of ammonia-nitrogen).

2.4 EEstimated Total Suspended Solids Production.

Ng et al. (1983)  observed that the maximum total suspended solids (TSS) production for poecilids is 27.6% of feed, quite close the 30% suggested by Colt (1986). I propose estimate TSS production as 30% of daily feed allowance.

2.5 EEstimated Total Phosphate Production.

Althought Ng et al. (1983) observed that the metodology in their experiment was not accurate to measure total  phosphate (TP) production. The best I can do for now is estimate TP production as 0.41% of daily feed allowance.

2.6 EEstimated Total Kjedhal Nitrogen Production.

Again, just like above, althought Ng et al. (1983) observed that the metodology in their experiment was not accurate to measure total Kjedahl nitrogen (TKN) production. I propose estimate TKJ as 3.037% of daily feed allowance.

2.7 EEstimated Carbon Dioxide Production.

Colt (1986) was the only one source I found to get data to estimate this parameter. He stated that 28% feed becames carbon dioxide (CO2).

3  – Total Dissolved Oxygen Demand.

gIn recirculating systems, there are many competitors for the available oxygen in the system. These include the fish, nitrifying bacteria (which break down ammonia and nitrite), and other bacteria that consume organic carbon in the system (commonly referred to as biochemical oxygen demand or BOD).h Hochheimer (no date).

Since there is no data on this subject for guppies Ifll perform another freak out. Ifll estimate the amount of oxygen that guppies demand for respiration, the amount of oxigen demanded by nitrification and BOD and Ifll compare this estimative to the data available for other species.

3.1 – Oxygen Demanded for Respiration.

Fishbase provide us with some data on the metabolic rates (oxygen consumption) of guppies. This data set was genereted for fishes at 20ºC, under normal swimming and at hipoxya (low oxygen) condition. I personally figured that there was too much variation in oxygen consumption they reported for fishes of the same sex and of the same size so I calculated the average oxygen consumption among each weight class and gender (table 3) and I submmited this data to the spreedsheet in order to  calculate tendence curves (figure 6).

Table 3 - Average Oxygen Consumption of Guppies  in Different Weight Classes and Gender at 20ºC.

Adapted from Fishbase.

Weight Class
(g)

Average Oxygen
Consumption
(mg /kg/h)

Observations
- n
Sex
0,01
850,40
5
Unsexed
0,02
604,60
5
Unsexed
0,03
544,40
5
Unsexed
0,04
539,33
3
Unsexed
0,05
627,00
2
Unsexed
0,06
550,67
3
Unsexed
0,09
564,00
1
Male
0,10
573,80
10
Male
0,11
499,25
4
Male
0,52
449,00
1
Female
0,97
218,00
1
Female
1,00
384,00
1
Female
1,05
255,50
2
Female
1,11
267,00
2
Female
1,14
196,00
1
Female

                                         .

Figure 6 – Estimated Oxygen Consumption of Guppies at 20ºC. Adapted from Fishbase.

Teo and Chen (1993) investigated the metabolic rates (oxygen consumption) of guppies classified  into 3 different sizes (large 1.150}0.350g; medium 0.531}0.105g and small 0.168}0.050g) under different conditions. The authors obseved: (1) medium and large guppies generally did not differ in their metabolic rates; (2) temperature effect was highly significant for medium and large guppies, higher temperatures higher metabolic rates; (3) at 30ºC small fishes showed significantly higher metabolic rates than medium and large guppies; (4) at 20ºC, without any anesthetic treatment, individual fish showed a significantly higher metabolic rates than fishes in group of 10; (5) after medium sized guppies were starved for 2 or 5 days, their metabolic rates were not affected at all; (6) at 25ºC, the metabolic rates of guppies were significantly affected by the water pH, lower pH higher metabolic rates; (7) ammonium significantly suppresed the oxygen consumption rates of guppies, higher ammonia level lower metabolic rares; (8) there was strong correlation between rates of oxygen consumption and ammoniun concentrations y = 0.40-0.006X with R²=0.827; (9) guppies in the dark consumed 0.49}0.02mg O2/g bw/h and guppies gunder normal laboratory lightning conditionsh consumed 0.44}0.05mg O2/g bw/h, without statistical significant differences; and (10) guppies in water containing 70-75ppm of carbon dioxide significantly consumed 35.6% less oxygen than those kept in control water at the same pH. Follow the graphs representing some obtained results and a table where I copiled estimatives of their data on oxygen consumption from different graphs for fishes under control condition but only under different temperature effect.

Figure 7 - Rates of Oxygen Consumption of Guppies of Different Sizes at Different Temperatures.

From Teo and Chen (1993).

Figure 8 – Effects of Grouping and 2-phenoxyethanol on the Oxygen Consumption of Guppies.

From Teo and Chen (1993).

 

Figure 9 – Effect of Estarvation on the Oxygen Consumption of Medium Guppies at Two Temperatures.

From Teo and Chen (1993).

 

Figure 10 – Effect of the pH of the Water on the Oxygen Consumption of guppies.

From Teo and Chen (1993).

Figure 11 – Effect of Different Concentrations of Ammonium in the Water on the Oxygen Consumption of Guppies.

From Teo and Chen (1993).

Table 4 – Oxygen Consumption of Guppies at Different Temperatures.

Adapted from Teo and Chen (1993).

Size Class

Size (g)

Oxygen Consumption (mg/g bw/h)

15ºC

20ºC

25ºC

30ºC

35ºC

Small

0,168

0,80

Medium

0,531

0,29

0,46

0,51

0,62

0,66

Medium

0,531

0,29

0,42

0,51

0,62

Medium

0,531

0,32

0,55

Medium - Average

0,29

0,40

0,52

0,62

0,66

Large

1,150

0,26

0,35

0,58

0,63

0,58

Large

1,150

0,26

0,40

0,56

0,64

Large - Average

0,26

0,38

0,57

0,63

0,58

Kramer and Mehegan (1981) studied the use of aquatic surface respiration (ASR) by guppies. ASR is a mechanism used by guppies to meet oxygen demand in hypoxic (low oxygen content) water, it is a specific position in which the head contacts the surface and the jaws open just beneath the surface, it is adopted in attempt to promote branchial respiration of the supposelly present oxygen rich water just beneath the surface. I personally correlate it to the specific need of the fish for oxygen. I suppose that fishes with higher oxygen demand should make use of ASR  earlier and keep it for more time than fishes with lower specif oxygen demand. The authors finded that: (1) guppies from different stocks of origin spent different times in ASR, gAt low oxygen (18 torr) laboratory-born guppies derived from stocks likely to experience deoxygenation spent less time in ASR than do guppies derived from stocks less likely to experience deoxygenation.h; (2) fishes of different sexes spent different times in ASR that was not due to differences in body size , gSmall males spent about the amount of time expected for females of similar size, while large males spent much less time in ASR than females of their size.h; (3) body size variation effected diferenttely the times spent by males or females in ASR, gThe percent time in ASR increases with increasing size of  female guppies, but decreases with increasing size of male guppies.h; (4) temperature effected the time spent in ASR, gThe percent time in ASR increases with temperature when PO2 is held constant.h; and (5) different sexes shown different responses to temperature, gFemales showed continual increase in ASR right up to 35ºC while males reached a peak at 32ºC.

I would like simply use the data from Fishbase to estimate oxygen consumption of guppies because their data shown a straight effect of fish size in their oxygen consumption rate. It was a dogma for me. But I knew that since their data is expressed in 20ºC basis and that they used hypoxia condition I should make any kind of adjustment to their data. I thought I just would need get the other article I had initialy refused, Teo and Chen (1993), and estimate adjustment factors for 30ºC that is around the temperature where guppies show the higher metabolic rates and also is around the temperature that we try raise them . I had initialy refused Teo and Chen (1993) data because their data didnt clearly fited my dogma, their medium fish is twice the mass of  large ones and both have the same oxygen demand???, I thought that happened due any problem on their metodology, perhaps because they just used 3 sizes of fishes while Fishbase used many more size classes. But both datasets simply didnft fit each other and I saw I would need a way to explain these differences, that was when I went to my home library I found this article from Kramer and Mehegan (1981). Right now, 5 days before the release of this issue, I got two more articles Post and Lee (1996) and Odell et al. (2003) that confused me a glittle bith more. Simply I had no time to digest all this stuff...

For a while, until our next issue, Ifll propose estimate the oxygen consumption of guppies as 1mg O2/g bw/h.

Table 5 – Differences in the Oxygen Consumption of Guppies  according to different sources of data*.

Size Class

Size (g)

Teo and Chen (1993).

Fishbase**

Diference***

Small

0,168

0,800

0,464

1,723

Medium - Average

0,531

0,615

0,349

1,764

Large - Average

1,150

0,623

0,271

2,297

                          * Expressed as (mg O2/g bw/h)         

                         ** Data calculated using equation O2 Consumption = (-100,37*LN(Size(g))+285,3)/1000

3.2 – Oxygen Demanded for TAN Oxidation.

Ebeling (no date) state that, stechyometrically speaking,  see item 2.2, for the complete oxidation on one gram of ammonia-nitrogen are burned 4.57g of oxygen. This same oxygen demand for TAN oxidation was used by Losordo and Hobbs (2000).

3.3 – Oxygen Demanded as Biochemical Oxygen Demand (BOD).

Ng et al. (1983)  estimated that for poecilids are demanded a maximum of 125.5 mg BOD/g feed/day or 12.55% of feed. See table 2.

4.4 – Total Dissolved Oxygen Demand in Feed Basis.

Losordo and Hobbs (2000)  wrote gWesters (1979) determined that for salmonids, 200–250g of oxygen are consumed per kg of feed input. Additionally, data presented by Thomas and Piedrahita (1997) indicates that the respiration rate of White Sturgeon (550g average wt, fed 2.5–3% of their body weight per day) varied from 290–385g O2/kg of feed. From these and other studies, we can assume this number varies between 200–500g O2/kg of feed (0.2–0.5kg O2/kg of feed).h Losordo and Hobbs (2000) used na estimative that 30% feed becames oxygen demand. I had no acess to the references they cited but I clearly see that they did not took nitrification into account because they added later to this initial estimative the amount of oxygen demanded for nitrification. Their overall estimative was that ~31.13 % feed becames oxygen demand for a feeding rate of  1.25% body weight and for a diet containing 38% crude protein.

Ebeling (no date) simply assumed that are demanded 0.4kg oxygen/kg feed, or 40% of feed, to design biofilters for cold water and warm water species.

Hochheimer and Wheaton (no date) misunderstood Colt (1986). gWith 187kg of feed fed per day, and assuming that 0.25kg of oxygen (0.21kg of oxygen per kg of feed (Colt,1986) plus na additional 20% as a safety factor) are required by the fish in the system for respiration and by bacterial respiration for nitrification  and cabonaceus biochemical oxygen demand.h. In a close reading of the original article by  Colt (1986) we clearly see that this author did not take into account the demand of oxygen for nitrification. He wrote about sizing a raceway flow-throught sytem, no nitrification envolved at all. 

 This model Ifm proposing estimated that ~53% of feed became oxygen demand. It is not much more than the maximum 50% estimated by Losordo and Hobbs (2000) and the 40% estimated by Ebeling (no date).

Any way  Ifll be working in the version 1.000000001 of this spread-something while you digest this one. 

Further References.

Ebeling, J. M. No date. Biofiltration. AES Workshop: Intensive Fin-Fish Systems and Technologies. p 47-56.

Itzkovich, J. 2002. Guppy culture thrives in Israel. Infofish International 4/2002:45-47.

Haskkell, D. C. 1955. Weight of fish per cubic foot of water in hatchery troughs and ponds. Progressive Fish Culturist 17:117-118 

Hochheimer, J. N. No date. Water chemistry in recycle systems.

Hochheimer, J. N. and F. W. Wheaton. No date. Biological filters: Trickling and RBC design. p 291-318.

Kaiser, H. and N. Vine. No date. Investigations into the growth, survival and fin quality of guppy, Poecilia reticulata, at different stocking densities. p161-168.

Kramer, D. L. and J. P. Mehegan. 1981. Aquatic surface respiration, na adptative response to hypoxia in the guppy, Poecilia reticulata (Pisces, Poeciliidae). Env. Biol. Fish. 6(3-4):299-313.

Liao, P. B. 1971. Water requirements of salmonids. Progressive Fish Culturist 32(4):210-224.

Phang, V. P. E and R. W. Doyle. 1989. Analysis of early growth of guppy strains, Poecilia reticulata, with different color patterns. Theoretical and Applied Genetics 77:645-650.

Shim, K. F. and J. R. Bajrai. 1982. Growth rates and food conversion in young guppy (Poecilia reticulata Peters) fed on natural and artificial foods. Singapore Journal of  Primary  Industries 10(1):26-38.

Teo, L. H. and T. W. Chen. 1993. A study of metabolic rates of Poecilia reticulata Peters under different conditions. Aquaculture and Fisheries Management 24:109-117. 

Thomas, S.L., Piedrahita, R.H., 1997. Oxygen consumption rates of white sturgeon under commercial culture conditions. Aquaculture Eng. 16, 227–238.

Westers, H., 1979. Principles of Intensive Fish Culture. Michigan Department of Natural Resources, Lansing, MI, USA, 108 pp.

Wheaton, F.W., Hochheimer, J.N., Kaiser, G.E., Malone, R.F., Krones, M.J., Libey, G.S., Easters,C.C., 1994. Nitrification filter design methods. In: Timmons, M.B., Losordo, T.M. (Eds.), Aquaculture Water Reuse Systems: Engineering Design and Management. Developments in Aquaculture and Fisheries Sciences, vol. 27. Elsevier, Amsterdam, pp. 127–171.

-Article Review:   By Enrique Patiño

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El

Genetic control of growth in the guppy

Editor's Notes: Discussion about quantitative genetics and heritability

Some useful links:
Quantitative Genetics

Quantitative traits are different from those inherited as Mendelian traits in that: 1- many genes are involved in their inheritance, 2- the phenotypes (traits) are "measurable attributes," and 3- the environment often plays an important role in the expression of the phenotype.

One can define Heritability for quantitative traits as follows:

Broad-Sense Hheritability = As a statistical calculation which defines heritability as the proportion of phenotypic variance attributable to the genetic variance in a population.

Narrow-Sense Heritability = Ratio of additive genetic variance to the total phenotypic variance (Additive Genetic Variance/Measured Phenotypic Variance). This definition is the most useful

In both cases, hertitability is defined as the extent to which individual (genetic) differences in the parent generation contribute to differences in observed phenotypic measures amongst individuals in subsequent generations. Assume you have two populations over several generations, one unselected and one selected. If the two populations started from the same gene pool, their performance (of the trait of interest - growth rate, for example) is relatively similar in the initial (P) generation. If the trait (phenotype) you are measuring is variable and part of that variation is heritable, the two populations should diverge over time and subsequent generations. If one calculates the difference in average performance between the selected and unselected populations in subsequent generations, one can come up with a realized heritability estimate. Realized heritability is an estimate of what the heritability needs to be in order to produce the rate of divergence given the type of selection practiced.

Because heritability is a ratio, its numerical value ranges from 0.0 (genes do not contribute at all to phenotypic differences amongst individuals in a population) to 1.0 (genes are the only reason for individual differences). Heritability estimates are very useful in predicting a response to selective breeding for quantitative traits such as growth rate in guppies.

Ryman (1972), for example, demonstrated that the guppy length at 63 days post-birth is heritable. What does this mean? This means that if we have an original population of guppies with a certain variability with respect to length at 63 days post-birth, and if we select the largest fish at 63 days post-birth as the breeders (directional selection), the offspring from these large breeders will, on average, be larger than offspring from the original unselected (random bred) group. As you can expect, directional selection for a quantitative trait with a heritability of 0.8 would yield a more pronounced response than for a trait for which the heritability is 0.2, for example.

Remember that the environment often plays an important role in the expression of a quantitative trait's phenotype. Just because you have differences in growth rates under certain growing conditions does not necessarily means that is a direct result of additive genetic variance. I say this because I've observed (not measured) differences in growth rate in batches of inbred guppies, and inbreeding should reduce genetic variance....The following article, however, summarizes in some detail the ...

Genetic control of growth in the guppy (Poecilia reticulata)

Authors: Masamichi Nakajima, Nobuhiko Taniguchi

Laboratory of Applied Population Genetics, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan

Scientific Journal: Aquaculture 204 (2002): 393E05

Body size, body length, and body weight (or growth characteristics) are quantitative traits, and are extremely variable in guppies. But, to what degree that is this phenotipic variation the result of additive genetic variance?

It is important to note that there may be changes in genetic control of growth at different ages in guppies. Nakajima and Fujio (1993) reported a change in the heritability of growth with age in guppies (this is also referred to as age-genotype interactions). Nakajima and Fujio (1993) suggested different genetic controls in three stages on the growth curve in guppies: 1 - maternal genotypic effects on the body size at birth (stage 1), 2 - growth genes in the growing stage (phase 2), and 3 - an inhibitory gene influencing final body size of male (phase 3).

Nakajima and Fujio (1993) also suggested that the genetic effect (contribution to heritability) from the maternal half (dam) for guppies would be different from the effect from the paternal half (sire).

Other Quantitative Traits In Guppies

Macaranas and Fujio (1987) and Barinova et al. (1997 and 1998) examined the genetic differences among some guppy strains by isozyme analysis (laboratory technique looking at differences in certain proteins, which reflect genetic differences within and between strains).

Macaranas and Fujio (1988) reported strain differences in four growth-related characteristics and in four reproductive traits in the guppy. These strain differences were caused by the genetic differences affecting each characteristic.

Nakajima and Fujio (1993) examined the genetic control for body length, Nakajima et al. (1995) for resistance to high salinity, Fujio et al. (1995) for thermal resistance, and Nakajima and Fujio (1999) for vertebral number.

Estimating the number of genes contributing to the genetic variance of the quantitative characteristics is fundamental for understanding the mechanisms of heredity for a given such trait. This is also true for the guppy. In guppies, Yamanaka et al. (1995) reported that there are approximately nine loci (n=9) affecting the male guppy body size at 180 days old. This was determined by crossing Fancy (F) and Standard (S strains), which have apparent (phenotypic) differences in the body length for males at 180 days old.

In their paper (this review), the authors estimated the variance components (contribution to phenotypic variance) from the maternal half (dam) and paternal half (sire) at different stages of growth, and strain differences of the body size at 180 days. They also estimated the number of loci affecting the guppy body size at 180 days old.

Materials and methods

Two guppy strains, F (Fancy) and S (Standard), were used. Both strains were maintained as a closed colony in the laboratory for at least 60 generations. These were maintained in 60-l aquaria with a density of 300E00 individuals per aquarium. For the growth profiles in this particular study, the drops obtained from single pair matings were reared in several 2.5-l aquaria and the density per aquarium was limited to a maximum of five individuals. The guppies were maintained at a temperature of 21-25 0C and fed a ground carp diet twice a day, with dried Daphnia given as a supplement. The standard body length was measured as an index of growth at 30 days interval from birth until 180 days old. It was only possible to determine the sex after reaching 60 days old, so, the measured values before 60 days old were pooled for females and males. The differences of the standard length between S and F strains and between sexes were tested by ANOVA (analysis of variance).

Results

The growth curve

The growth curve of the standard length and change of variance of the standard length at each age of the S and F strains are presented in Fig. 1. The means of the standard length at birth were 7.1 mm in the S strain and 6.9 mm in the F strain, respectively. The standard length of the S strain was significantly larger than that of the F strain at birth. The sex and strain differences could be observed after the fish were 60 days old. The females were always larger than males in each strain after reaching 60 days old and the F strain was constantly larger than the S strain for females and males after reaching 30 days old. At 180 days old, the means of the standard length were 23.1 mm in the S strain and 25.8 mm in the F strain for females, and were 15.9 mm in the S strain and 19.0 mm in the F strain for males. After reaching 90 days old, the growth rate for males dramatically decreases and stabilizes, however, a continuous growth rate was observed among the females. This tendency could be observed in both the S and F strain.

The change of variance

The different patterns were also observed in the change of variance of the standard length between females and males. The variance of the standard length was 0.081 in the S stain and 0.070 in the F strain at birth, and these values increased to 7.718 and 5.973 at 180 days old for females in both the S and F strains, respectively. On the other hand, the variance for males decreased from 3.298 and 2.569 at 60 days old, when the sex could not be detected, to 1.360 and 0.379 at 180 days old in the S and F strains, respectively. The variance in females continuously increased in growth, while, the males decreased until 120 days, then stabilized at a low value. In each of the family in each strain, the sex could be detected after reaching 60 days old. The male could be separated from the female by the existence of the gonopodium and body color after reaching 60 days old.

The distribution of the standard length

The distribution of the standard length in the S and F strains at 180 days old are presented in Fig. 2. The distribution of the S strain in males was clearly different from those of the F strain; But the difference was less clear in females. The smallest individual in the S strain was 17.0 for females and 14.4 for males, and that in the F strain was 22.5 for females and 17.2 for males. The maximum body size in the S strain was 28.47 for females and 17.3 for males, and that in the F strain was 31.8 for females and 21.7 for males. The overlap in the distribution was extremely small for males. The body size of the males in the S strain was clearly smaller than that of the F strain. The significant differences of the standard length were observed at birth and after reaching 60 days old between the S and F strains in each sex.

The fraction of each variance component

The fraction of each variance component to the total phenotypic variance and its fluctuations according to age and sex are presented in Table 1 and Fig. 4. The different patterns of fluctuations between dam component and sire component of variance were also observed between females and males. High fractions of the dam component were observed at birth. The fractions of the dam component in the females were constantly high, except at 60 days old, but those of the sire components had extremely low values. The males demonstrated a very different pattern of fluctuation in fraction in each of the variance pattern. The fraction of the dam components indicated a maximum value of 0.565 at 30 days old, and this decreased to 0.052 at 180 days old. In contrast, the fractions from the sire component increased from 0 at 60 days old to 0.831 with a maximum value at 180 days old. The sire variance component increased after reaching 60 days old, which marks the beginning of the maturation stage for male guppies in this study. These results indicate that the body size of a mature male is strongly influenced by the genetic factors from the sire, while the genetic factors from the dam were separated to two stages, one before reaching 30 days old and one after reaching 90 days old."

The effective number of loci contributing to the strain differences on standard length between S and F strains

Nakajima and Taniguchi (2004) obtained 80 offspring from the nine (SxF) crosses (females in the S strain and males in the F strain), and 193 offspring were obtained from the 14 (FxS) crosses, as the F1 generations. On the other hand, 201 offspring were obtained from the SxF and 186 offspring were obtained from the FxS, as the F2 generations. The standard length, its observed variance, and estimated effective number of loci are presented in Table 2. The standard length in F1 and F2 generations is distributed between the standard length of the parental strains.

Because there were clear strain differences at 180-days-old in each gender, the effective number of the loci affecting the strain differences on the standard length between the S and F strains were calculated at that point. The calculated numbers were 8.0 for females and 1.7 for males from the cross between the females in the S strain and males in the F strain (Table 2) , and 3.5 for females and a negative value for males from the cross between the females in the F strain and the males in the S strain. The negative value is due to the lower variance of the standard length in the F2 generation than that of the F1 generation. If the segregation of alleles affecting the strain differences occurred, the variance observed in the F2 generation was expected to be larger than the F1 generation. The low variation in the F2 generation from the cross between the F and S strains suggests that there is a strong genetic effect of the male in S, which is a small size strain.

Discussion

"Theoretically, heritabilities estimates have to range from 0 to 1.0. In this study, the variance components at several stages were estimated, and the patterns of fluctuation of the different dam and sire components were estimates and converted into heritability estimates, assuming autosomal inheritance, high values of more than 1.0 were obtained. There are some possible explanation for this...

If the genes of interest are located on the autosomes, both variance components from the maternal and paternal halves should have the same pattern of fluctuation. In the case of the X-linked inheritance, the sire is not a factor of variance because there is no X chromosomes from the sire in the male offspring. The female offspring get one X chromosome from the sire. In the case of the Y-linked inheritance, the factor of variance is only the Y chromosome in the male offspring. The low variance components from the paternal half (sire) and the high variance components from the maternal half (dam) in the female offspring suggest that growth characteristics in the female guppy are X-linked. The high variance components from the paternal half (sire) in the male offspring suggest that growth characteristics in the male guppy are Y-linked."

Nakajima and Fujio (1993) reported heritability estimates that changed according to age. They suggested that these changes in the heritability are due to three different genetic controls that occur during different growth phases of the guppy. These are: 1- the maternal genotypic effects on the body size at birth, 2- genes responsible for the growth in the growing stage, and 3- an inhibitory gene influencing the final body size for males.

"The results of this study suggest a strong genetic effect from the female parent on the early stage of growth.... There is a possibility that the maternal factors influence their offspring either through the egg quality, and/or by the environmental influences before birth."

The patters of fluctuation of the variance components for females were different from the patterns observed in males. This suggests there is different genetic controls of growth in both females and males. The growth rate of male guppies declines repidly after reaching 90 days old and almost stops, but females continue to grow (Figure 1). In this study, the variance from the sire components for females are extremely low, in contrast to that of the dam components, which came out to be very high values. High values of variance from the sire components were observed after 90 days for males. The standard length of a matured male is more directly influenced by the sire. "These results suggest that the gene(s) which influence the final body size of the male, is/are located on the sex-chromosome, and especificaly, that the gene(s) which influence the final body size of the male may be located on the Y-chromosome."

"In this study, the number of loci which affect the strain differences between the S and F strains at 180 days old were small, and ranged between 3.5 and 8.0 for females and up to 1.7 for males. The small number of loci estimated was similar to the value, of 9.0, estimated by Yamanaka et al. (1995). This calculation is valid on three conditions:

1 - all favourable alleles have been fixed at both strains;

2 - all the genes have equal effects;

3 - all genes have initial frequencies of 0.5 (Falconer, 1989).

Failure to meet conditions 1 or 2 leads to the under-estimation of the number of loci, and the failure to meet condition 3 leads to the overestimation of the number of loci. In this study, a negative value was obtained for the cross between the female in the F strain and the male in the S strain. It was caused by a smaller variance in the F2 the generation than in the F1 generation. In theory, larger variances have to be observed in the F2 generation over that of the F1 generation, which is caused by the segregation of the fixed genes at both strains. The loss of segregation in the F2 generation suggests that most of the gene(s) which lead the small size of the S strain are probably located on the sex chromosome.The number of loci may have been underestimated due to the possibility of the linkage between genes located on the sex chromosome.These results suggested that the small number of loci affects the matured male body size, and some of them are probably located on the Y-chromosome."

There have been some efforts in mapping of the locus affecting important quantitative traits in fish species using the molecular genetic markers (Lander and Botstein, 1989; . Berrettini et al., 1994; De Sanctis et al., 1995; Mole et al., 1996; Mousseau et al., 1998). This method can be used to further elucidate the genetic control of the growth in guppies. Hopefully researchers will continue to use the guppy as the experimental model for some of these studies.

ARTICLE REFERENCES

Barinova, A.A., Nakajima, M., Fujio, Y., 1997. Genetic differentiation of laboratory populations in the guppy Poecilia reticulsata. Fish Genet. Breed. Sci. 25, 19E6.

Barinova, A.A., Nakajima, M., Fujio, Y., 1998. Genetic variability and differentiation of both cultured strains and natural populations in the guppy Poecilia reticulata. Fisheries Sci. 64, 898E02.

Berrettini, W.H., Ferraro, T.N., Alexander, R.C., Buchberg, A.M., Vogel, H.W., 1994. Quantitative trait loci mapping of three loci controlling morphine preference using inbred mouse strains. Nature Genet. 7, 54E8.

De Sanctis, G.T., Merchant, M., Beier, D.R., Dredge, R.D., Grobholz, J.K., Martin, T.R., Lander, E.S., Drazen, J.M., 1995. Quantitative locus analysis of airway hyperresponsiveness in mice. Nature Genet., 150E54.

Falconer, D.S., 1989. Selection: II. The results of experiments. Introduction to Quantitative Genetics, 3rd edn. Longman, New York, pp. 209E28.

Fujio, Y., Nakajima, M., Nagahama, Y., 1990. Detection of a low temperature-resistant gene in the guppy (Poecilia reticulata), with reference to sex-linked inheritance. Jpn. J. Genet. 65, 201E07.

Fujio, Y., Nakajima, M., Nomura, G., 1995. Selection response on thermal resistance of the guppy (Poecilia reticulata). Fisheries Sci. 61, 731E34.

Houde, A.E., 1992. Sex-linked heritability of a sexually selected character in a natural population of Poecilia reticulata Pisces: Poeciliidae guppies . Heredity 69, 229E35.

Kinghorn, B.P., 1983. A review of quantitative genetics in fish breeding. Aquaculture 31, 283E04.
Lande, R., 1981. The minimum number of genes contributing to quantitative variation between and within populations. Genetics 99, 541E53.

Lander, E.S., Botstein, D., 1989. Mapping mendelian factors underlying quantitative traits using RFLP linkage maps. Genetics 121, 185E99.

Macaranas, J.M., Fujio, Y., 1987. Genetic differences among strains of the guppy, Poecilia reticulata. Tohoku J. Agric. Res. 37, 75E5.

Macaranas, J.M., Fujio, Y., 1988. Strain differences and heterotic effects among three strains of the guppy, Poecilia reticulata. Tohoku J. Agric. Res. 39, 19E8.

Marteinsdottir, G., Steinarsson, A., 1998. Maternal influence on the size and viability of Iceland code Gadus morhua eggs and larvae. J. Fish Biol. 52, 1241E258.

Mole, J.A., Shendure, J., Pociask, K., Silver, L.M., 1996. Identification of sex-specific quantitative trait loci controlling alcohol preference in C57BLr6 mice. Nature Genet. 13, 147E53.

Mousseau, T.A., Ritland, K., Heath, D.D., 1998. A novel method for estimating heritability using molecular markers. Heredity 80, 218E24.

Nakajima, M., Fujio, Y., 1993. Genetic determination of the growth of the guppy. Nippon Suisan Gakkaishi 59, 461E64.

Nakajima, M., Fujio, Y., 1999. Sexual dimorphism in the number of abdominal vertebra in the guppy Poecilia reticulata. Tohoku J. Agric. Res. 49, 87E2.

Nakajima, M., Shikano, T., Fujio, Y., 1995. Selection for sea-water tolerance in the guppy. Fish Genet. Breed. Sci. 22, 59E5.

Nakajima, M., Takahashi, N., Fujio, Y., 1998. Genetic control and expression of the cobra pattern in the guppy Poecilia reticulata. Fish Genet. Breed. Sci. 26, 17E5.

Phang, V.P.E., Khoo, G., Ang, S.P., 1999. Interaction between the autosomal recessive bar gene and the Y-linked snakeskin body Ssb pattern gene in the guppy, Poecilia reticulata. Zool. Sci. 16, 905E08.

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Ryman, N., 1972. An Attempt to estimate the magnitude of additive genetic variation of body size in the guppy-fish, Lebistes reticulatus. Hereditas 71, 237E44.

Shikano, T., Nakadate, M., Nakajima, M., Fujio, Y., 1997. Heterosis and maternal effects in salinity tolerance of the guppy Poecilia reticulata. Fisheries Sci. 63, 893E96.

Tave, D., 1993. Genetics of quantitative phenotypes. Genetics for Fish Hatchery Managers, 2nd edn. An AVI book, New York, pp. 117E64.

Utting, S.D., Millican, P.F., 1997. Techniques for the hatchery conditioning of bivalve broodstocks and the subsequent effect on egg quality and larval viability. Aquaculture 155, 45E4.

Winge, O., 1923. Crossing-over between the X- and the Y-chromosome in Lebistes. J. Genet. 13, 201E17.

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-Guppy Aquaculture - Short Communications:  

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One Perspective About Guppy Aquaculture

Here in the USA, I have known many people for which their hobby is to brew their own top-quality beer in their "garage". Even if their product ends up being much more expensive that buying the mass produced beers or the more elaborate micro-brews, people take a lot of pride and enjoyment in the product of their "garage" operation. What is more, for those that know what they are doing, the quality of their product is tops.

Maybe because in addition to my formal training in aquaculture, I also have had the privilege of working in the biotechnology industry here in Seattle, that I consider rearing guppies as merely managing a bioreactor for the purpose of extracting a live product. What I am engaged is in a serious effort to do my own top-quality "micro-brew" at a "garage" level operation.

Below you can see how a set up of 18-liter and 1.5-liter containers can be used for maintaining 3 double sword strains. Some of the tanks can be used to raise lots of coral red double sword fry, some to house breeding groups. I just need to feed them adequately and provide them with good water, and I should be able to extract the live product of my bioreactor chamber at the proper time. For the coral red double sword fry chamber (right picture), the live product in the picture is my first breeding group about 5 months of age.

 

 

 

 

 

 

 

Whether I use a recirculating system or individual containers, the concept is the same.

 

One Way of Feeding Decapsulated Brine Srimp Eggs To Guppy Fry

One way of feeding decapsulated brine shrimp eggs to guppy fry is to hydrate the dry cysts in a dish (about 1 gram -depending on number of fish to feed) in 5 ml of water about five minutes prior to use. Using a spoon, continuously mix the suspension while dispensing the mix into the bare-bottom tanks. Some of the cysts will sink and some will float. Feed more than the fry will eat, unless you find that you are good at feeding just the right amount (judging from whether their abdominal cavity -stomachs- are full). Some of my tanks (strains?) are better at eating from the bottom of the tanks and some are better at eating from the surface. Siphon any uneaten food and waste about 20-30 minutes after feeding. If you have too much left over at the surface, splash the surface to sink the floating cysts before you siphon the tanks. You can also simply flush the tanks if water is not a limiting factor in your operation. You can follow this procedure more than once per day if this is the only food your fry are eating. At least once per day is recommended.

I have raised fry from birth on decapsulated brine shrimp eggs. But I think that live newly hatched brine shrimp (live food) is best for the first week or so. It is not a matter of nutritional content of the food. It is a matter of food intake and cleaning tanks (maintaining good water chemistry). It is easier to feed live brine shrimp if you are trying to avoid over feeding and minimize the system's (or labor) requirements to remove uneaten food and water treatment.

 

Recent Abstracts From Scientific Literature

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Effect of threadfin aquareovirus recombinant proteins on the resistance of guppy (Peocilia reticulata) to guppy aquareovirus infection

Authors: Sim, S.H.a; Seng, E.K.a; Lim, S.Y.b; Lam, T.J.a; Sin, Y.M.a
Source: Aquaculture 235 (2004): 123-138

Abstract: Two recombinant proteins obtained from the marine threadfin aquareovirus (TFV), representing the inner (rICP) (75 kDa) and outer (rOCP) (35 kDa) coat proteins of the virus were used to study their effects on the immunity of freshwater guppy (Poecilia reticulata), against guppy aquareovirus (GPV), a strain isolated from moribund guppy during a recent disease outbreak. Western blot analysis utilizing rabbit anti-GPV serum demonstrated that both the inner and outer coat proteins of the threadfin aquareovirus (TFV) share common epitopes with the native outer and inner viral coat proteins of guppy aquareovirus. The rabbit anti-GPV serum also exhibited neutralization activity against the guppy aquareovirus. Furthermore, both recombinant rICP and rOCP proteins could block GPV from infecting susceptible cultured cells. Hence, these two recombinant proteins were then assessed for their suitability as candidate vaccines against GPV in guppy through immersion and oral immunization. Immunization of guppy with recombinant rOCP and/or rICP resulted in the production of neutralizing substances. The neutralization titers of the tissue extracts obtained from guppy immunized orally or by immersion with either recombinant rOCP or rICP were lower (between 1:32 and 1:64) compared to those immunized with a combination of recombinant rOCP and rICP (1:1024). These results clearly indicated that the administration of a combination of recombinant rOCP and rICP for immunization is essential for the induction of high amounts of neutralization substances that prevents GPV infection in guppy.

Night feeding by guppies under predator release: Effects on growth and daytime courtship

Author(s): Fraser DF, Gilliam JF, Akkara JT, Albanese BW, Snider SB
Source: ECOLOGY 85 (2): 312-319 FEB 2004

Abstract: The nonlethal effects of predation threat can be pervasive but are also easily overlooked. We investigated effects of predation threat on feeding by guppies (Poecilia reticulata), and how threat-induced temporal shifts in feeding activity affect reproductive behavior and growth. Contrary to the view of the guppy as a "diurnal" species, our observations revealed that guppies free from severe predation threat expand their foraging into the nocturnal period. We found such nocturnal foraging to be as profitable as diurnal foraging, and guppies. under threat incurred a substantial growth penalty when predators inhibited night feeding. Denial of night feeding also decreased daytime courtship by males, facultatively duplicating a classical observation comparing courtship intensity in contrasting predator regimes, but providing a novel mechanism for the effect. Our findings support the view that evaluations of predator effects on life histories should consider potential predator-caused alterations in size-specific energetic gain, along with the classical consideration of predator-altered mortality rates. The results of this study show that predation threat can induce a large, facultative shift in the temporal niche and vital rates of a prey species. We discuss some implications of the effect in the broader contexts of predator facilitation, evolution of life histories, and trait-dependent decisions to boost daily intake by expanded feeding times.

Ultraviolet reflectance patterns of male guppies enhance their attractiveness to females

Author(s): Kodric-Brown A.; Johnson S.C.
Source: Animal Behaviour February 2002, vol. 63, no. 2, pp. 391-396(6)

Abstract: In many groups of fish male colour patterns reflect in the ultraviolet, but little is known about female preferences for these components of male ornaments. We studied UV-reflective colour patterns in male guppies, Poecilia reticulata, and their importance in female choice. Using photographs taken with a filter transmitting only short wavelengths, we found that 4-24% of the area of a male's colour pattern reflects in the UV. We measured female visual responses to paired males placed, alternately, behind UV-blocking and UV-transmitting Plexiglas partitions. When pairs were matched for carotenoid (red), structural (white) and UV-reflective colour patterns, females spent significantly greater amounts of time inspecting a male when he was behind the UV-transmitting partition. These results show that UV-reflective components of male colour patterns enhance their attractiveness to females. To determine whether level of predation affects female response to UV-reflective colour patterns, we tested females from two populations differing in predation pressure. Females from both populations preferred males viewed through the UV-transmitting partition. When females were presented with male pairs that differed in the area of UV reflectance but were matched for carotenoids and structural pigments, difference in the time spent with the males was positively correlated with difference in the area of UV reflectance. Our results indicate that UV-reflective colour patterns enhance male attractiveness to females and thus may be elaborated through sexual selection.

 

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