TJ Hudson who is a member on here and I found a source for a species of grass shrimp adapted to pond life. Fattig's in Nebraska sells them. TJ usually puts an order in for all members interested each spring so everyone gets a better price by bulk ordering. TJ is just a good guy and really gets nothing out of it but the feeling of being a nice guy... Snails often simply show up on their own. You can also collect them from the wild, but be careful as some species can cause problems. Also, the thinner shelled pond species are better as they are more preferred as prey by RES. I have at least 4 species in one pond with RES and the thin shelled varieties have gotten quite rare. The ramshorn species are less numerous but not so rare as they get bigger and adults are fairly safe from all but the largest RES which I don't have any right now as the RES aren't that old yet. I have also stocked Asiatic clams to add to the forage base of my RES, but most wouldn't recommend that as there are lots of unknowns with them.