HELP!! Possible ich on fish?
 

I have a bicolor blenny in my tank for about 2 months now, just two weeks ago I notices that he will sometime scratch on rock, but I am not seeing any visible white spot on him

He is still eating like a pig! I mean it, he eats alot! His tank mate are pipefish, mandarin, twin spot goby, and many inverts ( shrimps and crab).
There are 2 anemone ( RBTA, GBTA), green open brain, and 2 gorgonian.

Tank parameter
Ammonia :0
Nitrate :0
Nitrite :0
Phosphate :0-0.25
PH: 8.0

10% WC every weeks, 25% every 2 months.

This start happening after I added a sand sifting goby (twin spot) and my tank got little cloudy for a few days but now is cleaned up but the blenny is still scratching!

Any idea why is he doing that? Could it be ich or anything that is irritating him?

http://www.reefsanctuary.com/forums/...ths-facts.html

Read that, you might have to quarantine your fish, or leave them and hope for the best, if it is ick.
One of the first places ick goes is to the gills