When selecting fish species for an aquaponic system, consider factors like ideal water temperature range, availability of fingerlings to stock the system, maximum adult size and growth rates, market prices if selling the fish, and dietary needs. Popular aquaponic fish choices include tilapia, koi, goldfish, catfish, bluegill sunfish, rainbow trout, perch, carp, Arctic char, large mouth bass and barramundi. Ensure the fish species you select is compatible with your climate and available supplies in your region.