As you can see, he is covered in white crap. What do you think it is? First off, having successfully dealt with ich in a loach tank several months ago, I am pretty sure this isn't ich. For one thing, none of the other fish in the tank have been exhibiting any flashing, fast breathing, or any kind of stress, nor does Short Whiskers. Second, if you look closely, the spots are too fluffy and large to be ich. So what else might this be? If I were to guess, I would say it's a fungal infection, but other opinions would be much appreciated.
A little history on Short Whiskers might help. We bought him about two years ago. I think he came from the LFS with a latent fungal infection, as he had short and sad-looking fins and whiskers. About a month later, he was hit with either a bad case of fungus or columnaris that basically replaced his dorsal fin with a cottony ball of fungus. He looked so awful that we thought he was going to die, but after we moved him to a hospital tank and treated with nitrofurazone, the fungus went away completely. Not only that, but after giving him a second treatment of nitrofurazone a few months later, his dorsal fin grew back.
That was a year and a half ago. He's been fungus-free since then, although I always noticed that he was often covered with detritus from the bottom of the tank, more so than the other 20 bottom feeders in the tank. But the way he looked today made me wonder if the fungus is flaring up yet again. Is that even possible after such a long interval?
Regarding tank parameters, Short Whiskers lives in an 80-gallon tank with about 30 other fish, mostly small cories and loaches. We have another dianema in there, Long Whiskers, who is congenitally deformed, but isn't covered in this crap. Most everyone else in the tank is healthy; one of the loaches did come down with a fungus or columnaris infection last week, and is currently undergoing successful treatment in the hospital tank, but its white patches looked completely different. Water parameters are fairly normal (nitrite & ammonia 0ppm, nitrate 30ppm, pH 6.7, temp 76 F, low GH & KH).
With all that said, does anyone have any idea what this is, and what treatment you'd recommend? Whatever this is, it doesn't seem to be bothering Short Whiskers yet. If it does turn out to be fungal or bacterial, then he's off for yet another stint in the hospital tank. Fortunately, he tolerates it extremely well. Thanks in advance for any advice.