Fish aggression
 

Hello,

I have a 120 gallon with a mate pair of percula clown (1.5" and 3"), a yellow tang (3"), a hippo blue tang (3"), a lawn mower blenny, and two chromis.

This past week, th female clown has a gash on it side. Then today, it has a pretty deep cut under its chin. I cannot figure out which fish did it. The clown acts skittish around the hippo blue tang, but I think it's the yellow tang that is causing the problem. Unfortunately, all the damage occurred when I am not observing, so I don't know what fish is causing the problem. My GF things it's the hippo blue that is causing the injury - but I think it's more likely to be the yellow tang. I thought the hippo blue were pretty docile, while the yellow are aggressive. Comments?

Thanks
Minh

My vote would also be with the yellow but you can only know by observation.

Yellow tangs are of the devil.

I agree that the Yellow Tang is the perpetrator. They become notoriously aggressive whenever they choose to. Its like dealing with an unmedicated bi-polar individual. Things may get worse for you clown though. Good luck.