I have two ten gallon tanks. One holds three male Bettas (separated of course) and the other holds 3 female bettas, 2 platies, and an algae eater.
I noticed a little 'fungus' on one of my container males and I used malachite green/form treatment. I don't know if it was the Malachite or the fungus but he went fast. I figured it was the lack of heater in the container hindering his healing.
So I got the 10 gallon for the males.
They have a heater (tank kept at the rec'd 80 degrees), a strong filter with a flourescent light. Their NO2 tested normal. The same with the female tank.
But they keep getting the fungus.
No new fish, no new plants or items, I did take the carbon out when treating them.
My largest female in particular keeps getting 'cataracts' on her eyes. My blue female has a shredded tail fin. I've also lost a pleco and another algae eater.

My problem is..I don't know what I'm doing wrong. I tried the malachite green. It didn't do anything to the fungus on the fish.
Water change.
Stop at walmart, bought Jungle Fungus cure that has nitrofurazone, furazolidone, and potassium dicromate as the active ingredients.
It helped for a bit, but it's back again.
My pink male gained a pop-eye this round.
I considered salt..but saw the sideeffects.
I do have water cabbage and a dwarf lotus plant in my tanks. So I have to take those into account.

Any help or suggestions would be a great help.