I just joined MFK. My Oscar "billy" my son named him got sick several months ago with a bacteria that was eating portions of head. I did several water changes, cleaned the filters and used melafix and Stress Zyme, which cured him completely, skin grew back nicely. But it just started happening again . It is not affecting the other fish Angels, clown loaches and Plecoptera. Has anyone experienced this? I am repeating the process, any suggestions are appreciated. He is in a 55 gallon, tank with two 45 gl rated filters for over filtering. Temp is 80 to 82. All are peaceful. Occasionally the oscar and Plecoptera get on each other's nerves. I will up load a pic of Billy's head. Thank Alan