I had a (not pea) puffer (Ichabod Crane) in a 15g. I didn't want/have room to set up in the 15 g again so I put him in my 22g with my 7 eyespot gourami, 3 scarlet badis, few anchor cats and a couple of small BN fry I was growing out. The puffer killed or fatally damaged the gouramis (under skin hemorrhaging), killed the scarlet badis (ate parts of them!) and one anchor cat. He was separated and floating in another tank temporarily so I could figure out what to do with the berserker. I hated re-homing him so I put him in the 120g thinking its 4'x2'x2' so how much damage can he do? Was OK for 3 days and the other morning one of my Laetacara curviceps was dead and half of the flesh from the peduncle to the anal fin on his right side was eaten. All the other fish were fine, no heavy breathing, clamped fins, red streaks. I did an 50% WC and added some stress coat along with Safe to condition the water.
Everyone was OK all day and then this morning I find two more Laetacara curviceps dead and one emerald cory. The curvicep had hemorrhaging across its body matching the marking on the eye spot gouramis that died in the 22g. The other had numerous bite marks on its tail and ventral side. One of my emerald cory was dead as well-both eyes eaten and some hemorrhaging under the skin by its gills. Took me five minutes to realize the pucking puffer was killing my fish as they sleep at night! Just in case it was not the ?puffer, I did another 50% WC. I did catch that little pooper and he is in a bucket. I am going to wait to see if there are anymore mysterious overnight deaths now that Ichabodthe (pooper) puffer is out. If not he is going to go to a local fish store-Fish Planet, to be re-homed the murderer. Should have called him Norman (Bates)!