Bonnie & Clyde Clownfish

[HD_Reefer]

So I have a bonded pair of Clownfish that until last night, have been living peacefully with a juvenile Mimic Tang. There has never been any aggression at all in the 24g and all have been perfectly happy. I walked by the tank this morning around 7, long before the lights come on and see both Clowns physically beating on the Tang. They had her in the corner of the tank and seemed to be taking turns swimming around and ramming her into the glass. It had obviously been going on for a while because the tang had just given up and wasn't even trying to get away.

I got the Tang out and moved her over to my other unoccupied tank, but it was too late. She never recovered and passed away after an hour or so. Her tail fin was all but gone and her left fin was barely still attached.

Nothing has changed in the 24g and the parameter are perfect. The Clowns are 2+ years old, so I am wondering if maybe there's some babies on the way that caused the aggression. I looked around the tank, but can't see any eggs anywhere, although the male does seem to be lurking around the underside of the hairy mushrooms more than usual.

Any other ideas as to what might have caused this? It was wild watching the normally very docile Clowns be stone cold killers!

 

[Peace River]

Wow - I'm sorry to hear about your situation and the stress to you and the tang. Clownfish are wired for dominance and the accompanying aggression. Usually it is directed toward other clowns as a fish vies for dominance. Unfortunately, this aggression can be directed at other things as well whether it is another fish, shrimp, crab, coral, rock, or even your hand. I am a fan of clownfish and would love to tell you that this is unusual, but sadly I was disheartened by your story, but not shocked at their behavior.