i had some. you are going to need brackish water and feed them stuff like snails to keep their teeth from overgrowing. you might have to keep them in a species tank cause they are nippers. i guess they swim to the top of the tank if it looks like you are going to feed them but then almost all fish do that once they get used to the routine.
yeah keep them in a species tank, or with bumblebee gobies. it seems that either the other fish you put in there is either too slow and it will get nipped, or it is too fast and they nip the puffer.