i just bought 3 dwarf puffers. mine havent puffed yet. i think i have 1 male and two females because one is more aggro than the other two. i'm not completely sure yet because they are still too young to sex. its soo funny though because i just put snails in there and this one turned really dark and started attacking them! lol. he returned to his normal color after he ate all their antennaes (sp)