I have a Spotted Hawaiian Puffer in my 55, and the only thing he's ever attacked are my narcariuss snails. He liked their antennae that they probe with. He doesn't mess with my astro/turbo snails, hermits, sally lightfoot, emarald crabs, or my coral banded shrimp. My coral banded popped him one the other day fighting over a piece of shrimp. Not sure how big they get, but mine's only around 2" long. They're not as animated as a dog face or porky puffer, but he does have an attitude.