Treating My Tetras

[rewlyn]

hi guys its been a month or two, the other day my fire tetra(not sure its like a red conga) got sick it had boggley eyes and had white fungus growing on it, i treated the tank with multi cure, my tetra seems to be getting better (no more fungus) and now it seems his mate has got it, i have a mix of 20 odd fish, the rest seem alright, is this contaiges, should i remove those 2 tetras and why did only my red and pink gravel substrate turn black an blue

 

[KittyKat]

Either your gravel was dyed and the colouring has now washed off, or you might have a problem with nitrifying bacteria and/or cyanobacteria. No cyanobacteria induced algae anywhere? Stir your gravel regularly?

It is probably, at least mildly, contagious.. but the rest probably already have it. It is always good practice to isolate diseased fish and treat them on their own while keeping an eye on the main tank. If it worked once, it will probably work again so try applying another cycle of the same meds.