my daughter bought 4 orandas about 3 weeks ago. One of them now appears fat and spending most of the time on the bottom of the tank lifeless, although swims to the top as soon as she goes to feed them, it like one other appears to have white spots on the tail and i am unsure if this is ich or markings of the fish. They dont appear to have them anywhere else and the other fish is swimming about as normal. any ideas what could be wrong, im worried she has been over feeding and have told her not to feed for a couple of days