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.
Ramshorn snails (Planorbidae sp.) in both Brown and Red.
Malaysian Trumpet Snails. (Melanoides tuberculata)
Common Pond Snails. (Physa sp.)