If they get in the mood
then they will work on snails as well, but in a fry tank, doubt they would look to the snails for snacks.. have a couple of them, got them at about an inch each, but are now closer to 3.. they are quite nippy, and very territorial to each other, for the most part, they are leaving the 9 black skirt tetras, 4 Ottos, and 3 albino corie tank mates alone.. getting ready to add a few angels to the mix, so will have to see how they handle them.. personally, have regretted getting them, but with 6 tanks now, I have room to keep them seperated if needed. )