Yes- the smallest and small snails of hard thick shelled species compared to those large adult individuals will be easier to eat by snail eating fish. Catfish can and do eat large snails and clams - depending on size and specie of catfish.
This from Minnesota DNR - Channel catfish eat crayfish, insects,
snails, small clams, worms, fish, and the seeds of elm and silver maple trees. They primarily feed at night, which is the best time to catch them.
This from In-fisherman magazine –
https://www.in-fisherman.com/editorial/blue-catfish-baitfish-and-mussels/154642#replay
