spotted puffer

Question
Hello i have a 30 gallon fish tank with a small pleco,3 inch tiger oscar, firemouth cichlid and a spotted puffer(all freshwater). I got my spotted puffer a few days ago and he was fine, but he bit my firemouths fin, then he bit my oscars fins all over plus he bit the oscars lip. and i was just wondering if theres a way to keep the puffer from biting the other fishes fins? Thank you and please write back.

Answer
Hi,
Puffers are very nippy little fish.

My theory as to why has to do with their beaks. If they aren't constantly nipping things, their beak keeps growing to the point where they can't open their mouths. That part is confirmed true.

I feed mine a bunch of small snails, like the ram's horn and other "pest" snails that are introduced to the aquarium on plants. The hard shell helps keep their beaks down, feeds them, and finally lowers aggression.