spot, our dog-faced puffer, puffed up to about three times his normal size. it's the first time he's done it since we got him. why would he puff up? the only fish that has acted aggressive to him was our ocellaris clown, who was on the other side of the tank hangin' with our new clarkii clown. he was staring at the mirror, so maybe he puffed up to see what he would look like? what other things would make spot puff up?