My little blue tang went through the overflow teeth into the sump 3 times the first week. I cut a piece of coarse filter sponge and stuffed it into the overflow box. Worked great and when the sponge got dirty, just rinse it out (don't know if it would work with your HOB overflow). Once he gets a bit bigger and finds a good place to sleep at night , you won't have to worry about it. I have no idea if the scales will grow back. I fattened mine up quickly with varied diet of frozen mysis, Rod's food, hikari small pellets, arctic pods, and cyclopeeze. One good tip I got was to break off a small piece of the algae sheet and rub it between your fingers underwater so it breaks into small bits in the water flow....they seem to go crazy for that. Good luck