Put one in and let us know. Just kidding. Actually yes they can. I had a Royal Gramma in my Fuge for a while and he was fine. I also had my scooter blennie in there for a while. Just be careful if you put it in the sump, that he cant get sucked into the return pump.
I don't mind as much as long as they don't eat the macroalgaes there...
i am more concerned with the flow rate, it'll be 1200gph down there, think two clowns can handle it?