- I am hoping that somebody can find a solution for fin rot. I have
three fish (Bala Shark, Silver Dollar Red Hook, and an Irridescent
Shark) all 5-7 inches in a 40 gallon tank with a Fluval 304
canister filter. I change the water 5 gallons per week. I treat the
water with Nova Aqua and AmQuel before adding to the tank.
The ammonia and nitrate levels are normal and the water is
crystal clear. Every 2-3 months my fish get fin rot, I treat with
Maracyn for 5-10 days and it goes away for awhile but always
comes back. I am currently treating them with Maracyn for about
the tenth time in almost two years. It's driving me crazy. Does
anybody know why it keeps coming back?