Aquatic Snails.
Love them or hate them snails are a part of most natural aquatic environments, they scavenge uneaten food, algae and some even dig in the substrate which helps prevent it compacting. I have also found them to be good at cleaning up bad or fungused eggs in my breeding tanks.
Because I have puffers, and they all need snails as part of their diet I have several snail farms set up to provide a constant supply.
The excess I sell on Trade Me as Puffer Feeding Packs, or just Snails for anyone wanting to add them to an Aquarium.
I have
Ramshorn snails (Planorbidae sp.) in both Brown and Red.
Malaysian Trumpet Snails. (Melanoides tuberculata)
Common Pond Snails. (Physa sp.)