10 gal heated filtered tank, divided into 5 gal. On one side is a betta i've had two years. On the other is a delta that i bought 3 months ago (and who has chewed off half his tail, but thats another story).
the older fish had signs of white cottony patches on his head and body. I put him in a hospital tank with malachite green.. Two treatments (two days) and he seems to be responding well and improving.
Came home from work, and the delta (still in the big tank) now has the same signs. At this point, do I just drop my other fish back in the tank and treat the whole tank? I had wanted to avoid it because malachite stains the tank.