Symptoms of a nipping fish?

[Murraydar]

So a few of the acro frags in my tank are showing very little polyp extension and are losing color and flesh in spots. I noticed that my little yellow clown goby likes to perch on them. I just found out that they like to munch on them too.

Assuming he is nipping at the corals, would that be enough to cause the polyps to constantly be hidden and have major color loss? And should they be extending when he's not around? Thanks.

 

[DeniseAndy]

Yellow clown gobies can be touch and go. I had a pair for years in a sps tank and they made one of my staghorns their coral. They killed off a section and used it for laying eggs. Did not harm the colony. Now, if I put in a new small frag, they constant touching would cause problems. In fact when I lost the female to egg bound issues after 3 years, the male went nuts and began going after all the sps. Sitting, perching, constantly bothering them. He died shortly later though. Not before killing a few smaller pieces though.

Generally a healthy, mature colony can handle them, but sometimes the frags will end up not so good.

 

[Murraydar]

Yeah these frags are only about an inch long so I'm guessing they can't handle much stress. They're really beat up while most of my other sps are fine. These are the only ones I've seen him perching on.

I'll put him in the sump tonight if I can catch him and see how the corals respond. Thanks.