fin rot fear

[Mindy2400]

OK, I have a community tropical tank, 65 gallon understocked with 2 angelfish For tetris 3 green catfish one peppered Cory cat and a couple of very small algae eaters. My angelfish has come down with fin and tail rot and I need to treat immediately. I have a read for my son but I'm not sure if I can treat my community tank with this. All the water parameters are good 0 nitrates 0 ammonia ph 7. I have a hang on the back filter for up to 75 gallon tanks and I also have a sponge filter that is also rated for up to 75 gallon tanks. Tank is heavily planted

 

[Laser]

Since you have a cory catfish it's important not to treat with aquarium salt. If the disease has not progressed too far I would start by performing frequent water changes, perhaps everyday or every other day. I would do 50%, but no less than 25%. In my experience that is enough to reverse the effects of fin rot.

Do you have any pictures you could share with us?