Aggressive Clowns

[clownguy]

I have a mated pair of ocellaris clownfish. I had them in a tank with 1 neon dottyback. They lived peacefully for many months. Then out of the blue the clowns attacked and killed the dottyback. Is this unusual behavior ?

 

[rbaldino]

And everyone thinks that only damsels kill other fish...
I wouldn't call it unusual, but certainly not typical. Clowns are capable of being quite aggressive. I would guess that they're still maturing, and maybe they reached a point where they might actually mate and began to percieve the dottyback as a real threat.