I just recently upgraded my 29 gallon to a 55 gallon. With this extra space I wanted to add a synodontis to my pair. Aquadvisor suggests at least 3 in a group so I figured I would make it 3. Went to a fish swap yesterday and got a nice syno that was a little lighter then the others so he would stick out and add some contrast to my group. Got home put him in with the others and noticed immediately that 1 of my synos is chubby while the other is skinny and this guy is skinny to. Well the skinny guy I already had just won't leave the new guy alone I assume from the behaviour skinny ones mean male. He was Headbutting him repeatedly and nudging him like crazy, the new guy of course was scared to death and just wanted to hide but my guy was relentless. But the lights went off and I figured they would settle down. I get home from work today and the new guy is hiding in a plant on the other side of the tank and he is really close to the glass so I get a close up, he has marks all over him like bruises and scrapes. I watch them for a little bit and the skinny guy tracks him down again and just starts beating on him again. The new guy is about a half inch smaller and I am worried he will get killed. They have only been together about 24 hours now, will they bond is he just trying to check the guy out or is he abusing him. And if so why are thought they were fish that liked swimming in groups.