Basically the title pretty much sums it up! It has been a ongoing thing with my Angels for months which are prone to it due to their long soft fins and I am fed up with it and did some major cleaning today! I've read that that bacteria is like ICH, it's already in your tank waiting or it's introduced by other fish that are infected and gets in through their feces if the new fish are not quarantined. I've tried Melafix & water changes quit a few times but it just ends up coming back. Stress, overcrowding, fish that are not compatible can lead to aggression with fin-nipping, the wounds are an ideal breeding ground for the bacteria. But all my fish are compatible, water parameters are 0,0 and some nitrAtes and I do weely water changes of 25% with gravel vac. The finrot was caused by not properly cycling the tank over a year ago , so bad water quaility is the cause, I didnt know then. I read taking out all the ornaments and bleaching them was a treatment thus will be eliminating breeding grounds for the bacteria. So, I basically just took out all the decor, fake plants and bleached them. Whiped down the inside of the tank and did a good gravel vac because there was no way I was going to take the gravel out and bleach that. The filters I did not touch. I will be adding Melafix daily with small partial water changes for at least 10 days and see how this works. wish me luck!