于 2002-09-04 03:29 Don't worry, most of the wrasses (which doctor fish is one of them) will secrete a cocoon to cover itself when it sleeps so as to cover its smell from its predators. The cocoon will do no harm, or I should say nothing that I know of, I have kept this fish for 1 year and I never clean the cocoon. It disappears itself sometime later, not sure whether it decomposes or mixed with sand though.