@Puffergurl: That makes sense but I seem to be having the opposite problem in my tank. There are a lot of guppies in the tank and they have been picking on my pea puffer during meal time. When I break out the bloodworms the guppies will actually nip at my puffer to chase him/her away. He/she retreats usually to the bottom of the tank and hopes get what little they miss. (I make sure he/she gets fed)

This seems to contradict everything I've heard about puffers. Will my little guy/girl become more agressive in time? Any way to tell what sex my puffer is?

Any help is welcome.