I'm just guessing here but fresh water clams seem like they could work in aquaponics. In a fish tank they are hard to keep due to lack of food for a filter feeder.

Also check out the self cloning crayfish (Procambarus Marmorkrebs), Not sure if you can eat them but I had to pay 25 bucks for mine and they pop out 20 to 200 clones based on age every 20 to 40 days.