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HI all, I have a 29 gallon aquarium with 3 angels, 6 bloodfin tetras, 3 gold barbs, 2 khuli loaches, a female betta, a pearl gourami, and a mystery snail. It has a sponge filter. My bloodfins seem to have white spots on them. Almost looks like mold. I've treated the tank with melafix for a week...