I started my tank about 9-10 months ago and added a pair of clowns after cycling. I was worried at first too, but after all they are CLOWNS! Jk, but seriously I thought mine were dying as they lay on their side and float around the top of the tank at night. But I haven't had any problems so I assume it's normal behavior.
Now my bi-color blenny, he is just a goofball.