Google offers conflicting information about this. One article states it's not a true fungus but a bacterial infection while another states it IS a true fungus with an entirely different scientific name.
It does list fraying of fins among the symptoms, as well as the cotton puffs around the mouth and elsewhere on the body. In the case of my one Hi-Fin, the cottony puff was inside of its mouth, which he would open very widely then close again, in what appeared to be a labored effort. Ordinarily, Hi-Fins don't sit on the substrate and gape open their mouths slowly and widely. Their normal sucker behavior is to move very rapidly with short sucking motions along the way on some definite structure or structures in the tank.
The hanging in mid-water with a sideways tilt or riding of currents sideways wasn't mentioned in the articles I read, but I would assume the disease eventually would affect the swim bladder. That doesn't explain why the Hi-Fin that rode the current was still able to swim normally once he exited the airstone's current. For that matter, why was he even riding the current to begin with? Was it simply an easy way to conserve energy? Is it possible that the fish became trapped in the current and was unable to escape it for awhile? I know that Hi-Fins prefer fast-moving water, so it shouldn't have been an issue. The other fish that hung motionlessly in the water with a sideways tilt would also tilt sideways when resting on the substrate. These were the only symptoms I saw, and they differed in the two fishes.
Among the causes listed is poor water quality, which I know isn't the case in my tank, overstocking, which is the case in my tank, and stress from being harassed by other fish, which, to the best of my knowledge, has never occurred to my Hi-Fins. Also, warmer water temperatures, which doesn't apply to my tank, since it's coldwater.
Apparently, Melafix and Pimafix are ineffective treatments, as neither are mentioned in the articles I read. Instead, the Maricyn treatments are recommended. Treating with Maricyn (sp?) must be done outside of the tank if there are invertibrates such as shrimp or snails.
The only cause I can think of in my case was stress from overstocking. I do have to keep tabs on my nitrates, and do frequent water changes and gravel vacuuming to control them. I also have a very power hob filter on the tank in addition to the 4" airstone.
I am concluding it is very likely this cotton wool disease is what they both had, as at least some of the symtoms and causes were present. The google articles said nothing about it being contagious to other fish, and since the rest of mine remain healthy (for now), I am assuming it isn't contagious.
-- bigmamafish
