Big snails are in no danger. The only way the Valenti will be eating a snail is if it falls off the rockwork, on the SB upside down; then the Toby will be picking at the exposed snail. It's a possiblity they'll nip small hermits, and even kill some if they can get their narrow snout in the entrance of the shell. Large hermits would be in no danger, and I would hardly call these little puffers preadatory fish as the classification they are labled in. The two things I that would be in danger with these little guys, {as I've seen it first hand} would be long-spine urchins, and any spiny-box puffer thats smaller than the Toby. I've witnessed it first hand in a LFS, the Toby was nipping and pulling on the spines.