I bought an Achilles Tang a month ago. It was doing well. It was eating everything I offered, no signs of disease, and it seemed very content. It was picking at the rocks and swimming happily. This morning I go to feed the tank and he's dead for no apparent reason. There was no ich on him or anything. No marks that would indicate that he was attacked. I know Achilles Tangs are very touchy fish, but I thought that once you had them eating that they were good to go... I know Regal Angels are known to die randomly no matter how well they're doing for months or years. Are Achilles Tangs known to do that too?