Most aquaponics systems are designed around warmwater species. This is either due to a tropical location for the facility or the use of extensive heating systems to control water temperature in cooler climates. Warm water species tend to offer the highest conversion rates and short harvest windows, allowing for multiple harvests within a single year without complex staggering schedules. However, these fish also tend to produce very high dissolved nutrient levels compared to coldwater fish. This usually means scaling back the amount of plant growth per tank or expanding the biofiltration systems to compensate.

Tilapia

Tilapia is the single most popular fish species used for aquaponics as well as in the world of recirculating aquaculture. This fish combines a high conversion rate with a wide range of acceptable feeds to make for much lower feed bills than with species. Some fish require high-protein foods that cost more per pound to keep up a steady growth rate, but tilapia can be fed primarily grain-based feeds that are less expensive. They also freely breed every four to six weeks after a few months of growth. This can supply a free source of fry for replenishing your tanks if it’s worth the extra work to sort them out.

Water temperatures should be maintained above 55 degrees Fahrenheit at all times. Ideally, temperatures should be between 73-85 degrees F for optimal growth. Very high and low water temperatures will kill the tilapia. This species can handle a much wider range of pH, dissolved solids and oxygen levels than other types. Yet, they will grow slower in less than ideal conditions. The fast six to nine-month turnover rate, from hatching to harvest, is the biggest reason for their popularity. Keep in mind that tilapia has the most state bans against it in the US; including exclusion in Florida, Louisiana and more.

Channel Catfish

Catfish are far from the most luxurious or high-value fish, but there is a steady demand for fresh farmed supplies in many parts of the country. They’re also very reliable and relatively low-maintenance fish that can mature in as little as eight to ten months. However, they’ll need high temperatures and can’t handle dips much below 80 degrees F. Keeping the water around 85 degrees F or even above is preferred. Despite their reputation for eating anything, catfish actually require a high-protein diet, as they primarily eat small insects and other fish.

Perch

Perch is a great option for warm areas that can still experience serious cold snaps during the fall, early spring and winter. Many species of perch grow best between 70 and 80 degrees F but won’t stop growing until 55 to 60 degrees F. Occasional dips of temperature won’t put your fish harvest at risk when you’re growing silver or jade perch. Their carnivorous diet makes feeding these fish more expensive than other varieties, but the higher value for their meat can make up for the cost. The one drawback is a long maturation period. You’ll have to wait at least 16 months before harvesting, which is a long time for a carnivorous warmwater fish.