I threw one of the live mussels we were having for dinner last night into the tank thinking the puffers would get some good beak trimming as they chewed through the shell to get to the meat. Oddly enough they didn't really chew on it for long and are just ignoring it now. Even more oddly, the thing is still alive and kicking after having been in the tank for almost 24 hours now. Gonna ride this one out and see where it goes...