koi in tankThe Best Fish for Aquaponics

The first decision to make when selecting fish is if you plan to grow edible fish for harvest or ornamental fish for enjoyment. You can have both types living together in one tank. Other factors are growth rate to harvest, water temperature, tank size, etc.

Aquarium (ornamental) fish should be stocked at roughly 1″ per 1 gallon of water. That could be many smaller fish like guppies or dannos. It could also mean a few larger koi, pacu, or oscars.

Edible fish need at least 50 gallons of water to grow to a reasonable size. Less than this means ornamental, pond or aquarium fish are a good option.

By far, the most popular fish in aquaponics if tilapia. They have rapid growth rates, can handle a wide range of temperatures, and hardy, and are harvestable.

best fish for aquaponics

You’ll want to consider the natural environment that the fish species comes from to ensure that your aquaponic system can provide a similar environment. Trout, for example, like water temperatures below 65 degrees. Can your environment consistently provide this? If you are mixing fish species together in the same tank, be sure that they have similar living requirements (koi, tilapia, catfish). Do they all prefer the same water temperature, eat the same food, and have the same oxygen requirements?

best fish for aquaponics

  • Tilapia and catfish can grow in warmer water, but warmer than 75°F is not ideal for most plants, and can be a breeding ground for undesirable pests and diseases.
  • Water temperatures below 68°F are possible with various cool-water fish species, but nitrification and plant growth will slow substantially.

Because of the varying preferences of water temperatures, staying between 70-72° is a happy compromise that keeps bacteria, fish, and plants in a comfortable range. Trying to grow fish or plants outside the optimal range usually results in stress.

Don’t mix carnivorous fish (walleye) with herbivores, or you will find that you are just providing an expensive meal for your carnivores! We have found that tilapia, other cichlids such as oscars, pacu, goldfish, and koi all co-exist well together in an aquaponics system.

For more information on fish health, selection, and management, check out our Fish Health and Management Course.