Sleeper Gold Head Goby messing up my tank?

i have a 55 gal semi reef tank. i dont like the fact that i always have some sort of floating debris in the tank. i used to think its micro bubbles but they dont really float to the top, mostly just float around. its very clean at nightan din the morning whne the lights first turn on., but.... i think my Sleeper Gold Head Goby while he sifts the sand and the rocks, hes always picking up stuff of the orcks so im thinking that crap floating around is from him. anyone else had any problems? how can i catch that lil bugger?? ive tried but no way.... he just darts in the rocks.