Possible lymphocystis, not sure though.

[Colin_T]

Before you treat the tank, do the following things.

To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.
When you measure the height, measure from the top of the substrate to the top of the water level.

There is a calculator/ converter in the "FishForum.net Calculator" under "Useful Links" at the bottom of this page that will let you convert litres to gallons if you need it.

Remove carbon from the filter before treating or it will adsorb the medication and stop it working.

Wipe the inside of the glass down with a clean fish sponge.

Do a 75% water change and gravel clean the substrate. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash filter materials/ media in a bucket of tank water.

Increase surface turbulence/ aeration when using medications because they reduce the dissolved oxygen in the water.

 

[visions]

Thank you. I did as you said. He was in a bare tank to begin with but i cleaned everything nonetheless. He's had 3 days of the malachite green (Kordon rapid cure). As far as I can tell, he's not getting any worse and maybe a little better even. According to the package, Kordon rapid cure is fairly concentrated malachite green and a couple other ingredients ,is it safe to give the treatment for longer than the 3 days in the instructions? I know malachite green can be used longer than that, but I can find very little information on this particular product. I also started giving him metroplex orally again. I noticed the area on his fin closest to his body, where the most blood flow is, was getting better until I stopped giving it to him. That area has gotten worse and hasn't gotten better like it was before. It would break out in a few of the white spots, then it would go away. Earlier I posted it seemed like a cycle. That has stopped. And yes, the filter is less than 6 weeks old. After the biofilter crashed was when this all began.

 

[visions]

The fungus is gone it seems too. No more white/grey fuzz.