one of my fish has started to turn black (was BRIGHT yellow, now almost totally black) and can't swim properly, everytime he tries to go up he ends up sideways or going backwards.
Anyone know what is wrong with him??
what sort of info?? I don't know what else to say?? My water is fine, i've checked for everything (nitrites, nitrate, ph etc etc) all of my other fish (around 6 others) are fine, no signs of anything, it is a 180L tank roughly (4ft).