They don't eat the adults, just the little ones. I'm not sure at what size they eat them (in the egg sack? when first hatched?) but I do know that the Elassoma gilberti tanks I kept had a lower reproduction rate than tanks without the pygmy sunfish. The first freshwater tank I set up after keeping only Elassoma for a year shocked me with the rate of snail reproduction. It's a neolamprologus multifasciatus shell dwelling cichlid tank, where I guess the cichlids are somewhat symbiotic with snails and instinctively know not to eat them. So the snail population just exploded, it was ridiculous. I added some of our native carnivorous palaemonetes shrimp to eat the snails, and that's working well so far. Hmm maybe I'm getting off track. My point is: Will there still be a sustainable snail population in your Elassoma tank? Yes, they will breed and have a sustainable population. Will there be quite a lot of them? No, it's not the snail-splosion you see in other setups.
Edited by EricaLyons, 01 July 2013 - 03:18 PM.