Our first fish choice was channel catfish which turns out to have been a very good choice for outdoor aquaponics here in central Florida. Channel catfish can take the heat just as well as tilapia yet they can also handle the cold and will even keep growing well below the 70 degree F water temp that usually slows tilapia down. So in a non tropical and non climate controlled situation, catfish are likely to grow just as fast if not faster than tilapia.
Since flood and drain aquaponics tends to bring the water temperatures closer to air temperatures faster, having fish that can handle the warm and cool extremes can be a benefit. Channel Catfish certainly fall into this category.
Only a couple points about catfish make them slightly less hardy than tilapia; their need for slightly better aeration/water quality and their dislike of excessive handling. They are still rather hardy fish and completely reasonable for Aquaponics.
Channel Catfish are also native to the eastern United States. Channel Catfish is one of the most farmed fish and much research has been done in the field of catfish feed. This makes finding commercial feed for them quite easy and is a big topic for Aquaponics.
I’ve mostly fed Aquapmax 4000 feed to both my Channel Catfish and tilapia and that feed seems to provide good nutrient levels for the Aquaponics System and plants. I am still in search of alternative foods but haven’t found better yet. Catfish have a good feed conversion ratio (this means much of the food given is turned into meat rather than wasted.)
Channel Catfish have the benefit of getting BIG and this can mean less work to clean them to make a meal wen one fish will feed the whole family instead of having to clean lots of smaller fish. Aquaponic Catfish taste good and we have never experienced a “muddy” flavor from any of our Aquaponic fish. Can’t get much fresher than eating the fish only yards and hours from where and when it was caught.