Clowns don't normally have ick troubles. They are also sensitive to their diets and when first transported sensitive to the change in diet. Some species more than others; wild ones are more sensitive to all this that tank bred and raised. Feed him brine shrimp only for a while. If his digestive system is messed up, you may loose it anyway. They need to eat 2x daily - brine shrimp only until they are used to your tank. The brine only should go on for at least 2 months. Afterwards, change diets slowly if you think you need to. Ick can be helped to subside by raising the temp to around 84 degrees F and keeping it very stable even when the lights are off and on cold nights. Your QT water must be prime, 0 ammonia, 0 nitrite, 0 nitrate and have enough calcium in it. Can't be a trashy tank. If your QT is not all 0, get some of that "snake oil" I use called BacterVital. It has some good things in there and will help to get rid of the NH3 if there is any. Clowns like caves and they often lay on their sides. If you don't have any rocks in there, get a little clay flower pot and lay it on its side for them to hide in. Prop it some way so it won't roll around. No doubt there will be a hundred people chime in and disagree with me. I have around 50 clowns, pairs, babies, etc. Lost a high percentage of the wild caught ones, even from ASAS when they were in business. Clowns often don't fare well when shipped (mishandled) around the world. I wish you good luck.