I have recently acquired a breeding pair of discus, both seemed fine for the first month but my male has started to show like a fungal/mucus growth on his fins which now appear to be clamped and the females fins are clamped and she is rapidly breathing out of just one of her gills and both are now hardly feeding. I have tested water quality for ammonia, nitrite and nitrates and all is spot on but I have noticed today what looks like a very thin wriggly thread worm that is swimming around if you closely in the water and there seems to be several of these in the tank have you any suggestions at all as to what these can be?
Put the pair in a bare tank.
Treat them with Potassium Permanganate solution.
Repeat the treatment for a few days.
Rapid breathing show gill problems.