Which fish Is best for my aquaponics system? This inquiry is made by many students entering the field of aquaponics, and it is a very pertinent question so let’s talk about it!

There are a few areas of consideration that you should keep in mind while deciding the fish that is most suitable for your aquaponics system. You should take out a piece of paper and follow along with the considerations that are laid out in the next section to see which fish works best for your situation.

  • Suitability for tank culture - Tank culture involves raising fish at much higher densities than what would be observed in a natural environment. Any potential fish for aquaponics should be readily adaptable to crowding without compromising its growth and health. A fish that has been successfully raised in a recirculating system can be used as a guideline to know whether the fish in question is suitable for tank culture.
  • Intended use - What purpose do you have in mind for the potential fish? Do you just want to keep it as a pet, sell it to a local market, or do you want to raise it to be consumed by yourself and other family members? You should be as clear as possible regarding the intended use of your fish so you can make an accurate selection.
  • Climate - Growers should do a thorough investigation into the climate in which they reside. A proper understanding of your climate will give a good clue to the type of fish that can be raised without relying heavily on artificial heating and/or cooling. Fish metabolism is a largely a function of water temperature meaning that a temperature outside of what is optimum for the fish will decrease feed consumption, and as a result reduce nutrient production for your plants. A good practice is to select a fish that is well adapted to the environment in which it will be grown.
  • Local regulations - One of the most important consideration when selecting a fish is your local laws and regulations. Not all fish are treated equally in certain areas which places a limitation on the type of fish you can raise as an aquaponics growers. Some fish such as tilapia are deemed an invasive species in countries such as Australia and parts of the United States, and heavy penalties may be required if caught within an illegal species in your possession. Take the time to look into your county ordinances to see which fish are restricted in your area.

Now that we’ve covered some of the more important considerations for fish selection in aquaponics, let’s discuss some of the fish that have been previously used in recirculating systems so you can get a general idea of some of your options.

Rainbow Trout

Rainbow trout are a native species to lakes and streams located on the pacific coast of North America ranging from southern Alaska down to northern Mexico. Rainbow trout prefer cold water, and best feeding habits are observed when the water temperature is maintained between 14 to 16°C (57.2 - 60.8°F) (1). Rainbow trout have been traditionally used as a sport fish, but are also a highly delicate table fish consumed by many especially in the northwestern parts of the United States. These fish do exceptionally well in recirculating systems and are highly adaptable to crowding. A harvestable size fish is typically falls within the weight of 10 to 14 ounces (0.28 - 0.4 kg), which can be obtained in as little as 10 months (1).

Yellow Perch

Yellow Perch are found naturally in the region of the Great Lakes and Mississippi River basin. They are a cool water species with a preferential water temperature ranging from 23−26°C (73 -79°F) (2). Exposure to temperatures above 26°C (79°F) increases risk of disease and reduces growth (2). Yellow perch perform reasonable well in high density systems and can endure crowding and handling as long as temperatures are maintained below 24°C (75°F) (2). Harvestable size of this fish ranges from 120 - 150 grams and can be obtained within one year if optimum temperatures are maintained.

Bluegill

Bluegill are native to quite a large region ranging from parts of Canada stretching down to northern Mexico. Bluegill is a highly respective table fish in parts on Wisconsin and has reputed as the “bread and butter fish” due to it’s enjoyable taste (3). This species of Sunfish is typically accepted at a market size of 3/4 - 1 1/4 lb, which typically takes more than three years to obtain (3). Although bluegill are suitable for tank culture, they are probably most appropriate for personal use instead of commercial production due their prolonged growth period. The optimal water temperature 20–31°C (68–88°F) with the greatest grow occurring at a temperature of 31°C (88°F) (4).

Barramundi

Barramundi is an established table fish in countries such as India, Thailand, Vietnam, Malaysia, and Australia. These fish are protandrous hermaphrodites meaning they start their lives as male and then progressively change into females as they mature (5). This change from male to female is said to occur only in saltwater while barramundi that remain in freshwater will remain male in gender (5). Barramundi are a warm water fish that prefer water temperers within the range of 26 to 30°C (78.8 to 86°F) for optimal growth (6). Fingerlings can be reared to a tables size fish weighing 400 to 600 grams (14.12 to 21.16 ounces) in a matter of 12 months (6).

Channel Catfish

Channel catfish are a popular protein source particularly in the southern states of the United Sates. They are a warm water fish that grow well when temperatures are maintained between 23° to 30° C (73 to 86° F), and optimum growth occurs at 29.4°C (85°F) (7). Channel catfish do reasonably well in recirculating systems and can achieve a weight of 1 1/4 pound at approximately 18 months of age (7). The downside of growing catfish in highly dense areas is their susceptibility to disease such as columnaris when temperatures are on the high end for optimal growth (8).

Glass Eel

Glass eel are exception performers in recirculating systems with stocking densities ranging from 30 - 150 kg per cubic meter of water volume (8). They are a warm water species with peak growth occurring when water temperatures are maintained at 23-36°C (73.4 -96.8°F). They are reported to have an expected feed conversion ratio of 1.5 -1.6 which is good news for those looking to raise fish commercially (8). Glass eel have been successfully raised in recirculating systems in various parts of Europe to include countries such as the UK, France, Italy, Spain, and Portugal (8). They are consumed at high rates in the Japanese markets, but have not yet gained acceptance in the United States marker due to their snake like appearance.

Tilapia

Tilapia have been raise successfully in a number of recirculating systems for a number of years due to their hardy nature of being disease resistant and adaptable to poor water conditions. Tilapia are a warm water fish that thrive when temperatures are maintained within the range of 28 -35°C. A feed conversion ratio of 1.4 to 1.8 can be assumed with good feeding practices and quality pelleted feed. The accepted market size is generally around 1.5 lb for tilapia, but size can vary from as little as 3/4 lb to as high as 2 lb depending on the market demand (10).

Other notable mentions

  • Koi
  • Goldfish
  • Silver perch
  • Jade Perch
  • Murry cod
  • Sturgeon
  • largemouth bass
  • walleyes

References

  1. Rainbow Trout by Kathleen F. Ladewig and Michelle Morat
  2. Species Profile Yellow Perch by J.M. Hinshaw
  3. Fishes of Wisconsin by George C. Becker
  4. Sunfish Culture Guide by Joseph E. Morris, Charles C. Mischke, and Donald L. Garling
  5. Fisheries Fact Sheet By Government of Western Australia
  6. Agriculture Marketing Resource Center
  7. Channel Catfish Life History and Biology by Thomas L. Wellborn
  8. Columnaris Disease A Bacterial Infection Caused by Flavobacterium columnare by Robert Durborow, Ronald L. Thune, and John Hawke
  9. RAS Technologies for eels in Europe by Aquaculture and Fisheries Group, WU, WUR, The Netherlands
  10. Tank Culture of Tilapia by Dennis P. Delong, Thomas M Losordo, and James Rakocy