AI have several white clouds in a 20g planted tank along with several red rasboras and 3rosy tetras. They have been together for 2 to 3 years and all were healthy. one of the white cloud's head turned very black and his brown body color faded. After about a month, I put him in a 7gtank because I thought he might have neon tetra disease. he's been in this tank for several weeks--not geting better,but not worse either. His fins are still bright red. None of the other fish seem affected. Anybody have any ideas?