I had two otos, acquired at the same time (about six weeks ago) that were placed into a 20-gal tank w/ 3 platys and two mollies. One developed white patches about 2 wks ago & quickly died: today I see that the remaining oto has also developed the patches. It does NOT look like ick - more like the fish has rubbed off its "scales" (I know, catfish don't have scales, but you know what I mean!). My platys & mollies have all remained very healthy throughout. Any suggestions? I hate to medicate the tank for ich when I don't think that's what it is...but I could be wrong.