Fish pecking at rocks meaning

[Pimba]

So I got a bi color angel 2 days back. He is still not taking any prepared or frozen food but I see him pecking at rocks, glass etc.

Does this mean he is getting some food from pecking or it's just he is looking for food by pecking?

 

[davidcalgary29]

The bicolor angel, like many species of centropyge angels, is an omnivore, and gets a substantial portion of its diet from algae. Your rocks have microbial algal forests on them, and it's perfectly natural behaviour for your angel to be pecking at it for large portions of the day. I'd try to begin to feed your angel supplemental portions of nori on a clip -- soaked in selcon or not.