Help with Acropora

[migas_01]

My green acro has been doing ok however two or three days ago I saw one or two polyps without skin (I guess). Today three more
Do you think this looks like fish nipping? Or something ealse is wrong ?

thank you for helping.

 

[fastpcuser]

would maybe check for AEFW ... unless you have any fish nipping your corals

 

[mike_cmu04]

Looks like it could be a nipping fish.