yellow finned damsels are supposed to be more docile than most damsels. the only bad thing about adding damsels first is that they become territorial. so if they have staked there territory, then you clown might be in trouble. how big is the tank?
damsels are evil what kind of lights do you have is it a reef tank or fowlr cause if you like the clown you will feel obligated to get it an anename so it can hide from the evil devil fish. and then you have to buy strong lighting and then since you have the strong lighting you will spend a fortune on corals and before you know it your husband glares at you when you say your going to the lfs and your kids are complaing they need braces but you spend all your money on the stupid fish tanks their words not mine. save yourself alot of money just get rid of the five dollar evil fishies now.