Pet and Aquarium Stores: Just about any fresh water aquarium fish from a pet store works well as an aquaponics fish. Pay special attention to the temperature range that the fish thrives in, and whether they would be compatible with the other fish in your tank (i.e. not eat them). If your system is very small you might be able to stock your tank simply by visiting your local pet store. Pet store fish we have grown with success in aquaponics so far are goldfish (avoid feeder goldfish, they are prone to disease), koi, oscars, pacu, and guppies.
Hatcheries: More and more fish hatcheries are willing to sell small batches of fish to local aquaponic growers. If you have a hatchery nearby that is willing to sell to you this is a great option if you plan to grow fish to eat.
Online: You can look for local or national fisheries online and order many species through the web to arrive via mail. Please note that live fish are shipped with a limited oxygen supply, so make sure to receive them as soon as they arrive to ensure they don’t stress in extreme oxygen or temperature situations. Specific species may be prohibited in your area, so please be sure to check with your local regulations before ordering.