In this episode, Dr. Storey reviews the role of fish in an aquaponics system, gives a list of the pros and cons of the 8 most popular fish in aquaponics, and gives inside tips on how you can choose a great fish for your system.
How do fish work in an aquaponics system?
An aquaponics system is an ecosystem. The fish produce waste, the microbes break it down, and the plants use the waste nutrients. Then the water is cycled back to the fish.
The fish produce the majority of the nutrients for the plants. For the commercial grower, the fish also can be an important source of revenue. (Although there are many growers that keep fish for their aesthetic value.)
What are the most popular fish in aquaponics?
- Tilapia is one of the most popular fish for aquaponics use, because they are tolerant of poor water quality and high temperatures, they eat almost anything, and they breed readily. Pure bred Tilapia are rare, but it is only important to have pure bred Tilapia if you are cross breeding to produce sterile males. A drawback of Tilapia is that they are not cold tolerant and are illegal is some places.
- Another favorite is catfish. They are easy to get your hands on, they’ll eat just about anything, and they are tolerant of cold. They also put on weight really well. If you are selling your fish, catfish will be pretty easy to sell.
- Trout is another option. Trout can be finicky. They need high water quality and low temperatures, so you’ll probably need a water chiller of some sort if you want to use them. Trout are not our top recommendation.
- Yellow Perch are growing in popularity. We don’t recommend them because they are hard to get and need to be trained to take helated feed because they like live feed. They are hot on the market right now, however, because they are so delicious. Yellow Perch also require cool temperatures.
- Blue Gill is also becoming popular. They are similar to catfish as far as water quality tolerance goes, and people like to eat them. Make sure that they are legal to stock in your state.
- Common Carp is another one of our favorites. It’s popular throughout much of the world as a food fish, and it’s incredibly easy to raise. In the US there’s not a lot of acceptance, however, and in many places they are illegal because they are so invasive. They are tolerant of both high and low temperatures, they will eat anything, and they are tolerant of traumatic events. (Dr. Storey has found dried-out fish on the floor two hours after they jumped out of the tank, thrown them back in the tank, and had them survive.)
If you are keeping fish for aesthetic purposes, you’ll be thinking about goldfish and koi. (11:24 stopping point.)
Dr. Storey has kept some goldfish since he first started in aquaponics. They can be a lot of fun, though they are useless as food.
Koi are valuable for stocking in ornamental ponds. Ironically, koi are closely related common carp. (Although koi are legal in most places.) Like common carp, they are quite tolerant.
Four things to consider when stocking a fish:
- Environment: Water quality. Are you going to be running lots of solids? Has the water quality stabilized in your system yet? Ambient temperature and climate. Is the temperature right? Do the fish depend on light period for breeding? You want to match the fish to the environmental variable you are dealing with.
- Intended use: Are you going to sell the fish for food? Do you care about appearance and flavor? Do you care how well they are going to breed? Will you be stocking other tanks?
- Legality: This is important! Talk to your fish and game department. They will be able not only to tell you about legality of fish and legal sourcing, but may hook you up with good hatcheries as well.
- Costs: What are the costs of owning the fish and growing them to maturity? What kind of feed will you be buying? What kind of protein content do you need? (We recommend high quality and high protein feed for aquaponics fish in general because it gives better plant production.) What return on investment will you be getting?
This is not a comprehensive guide, but it is a good launching point. Now it’s up to you to go out and do your research and run up some calculations. Good luck!
Stay tuned for more information on fish and aquaponics.
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