Black blenny attacking Diamond Goby

[smcdonn]

My black blenny attacked a lawnmower a while back so I took the lawnmower out and put him in my QT. I have been wanting a sand sifter so I got a diamond goby thinking that he should be fine. Well now my black blenny is attacking my new diamond goby. There is no way I can get the black blenny out without tearing down the tank. Just leave them and see what happens? Are black blennys always this mean? thanks for any help.

[FMarini]

no black blennys are not mean, they are territorial. They see the lawnmower as a competitor for food. Pretty common situation, so you need to decide the black blenny, or a lawnmower but not both. ALso consider not getting any other blennys as well