Can you post a pic?
What size tanks and are they housed together
What are the water pram numbers: ammonia, nitrite, nitrate, pH, water temp
Water changes how much and how often and when was the last one
Treatments and medications, what have you tried so far and has anything worked, made it better, worse, no change
Additives used...how much, what for
Any other fish, snails, shrimp etc... in the tanks with them
Symptoms, before, during, after...flashing, wounds, discoloration, behavior changes, appetite etc......
Food, type and amount, frequency
How old are the fish.....
Any new fish added, if so, when and did you QT
I know lots of questions but this will help narrow it down......