Let me bring you guys up to speed......I have 2 large oscars in a 55G bare bottom tank with airstones, heater and a HOB filter. I do a 50% w/c every week and feed them once a day without over feeding them. As I fed then today I noticed these whitish blotches in the head area. First word that came out of my mouth was "*****, they're getting HITH." Now this would be my first experience with HITH, so I'm not positive that it is. Also the water was way warmer than normal. I don't have a thermometer, but I could tell it was warmer just by dipping my finger in the water. One of them must have moved the setting on my heater. Anyways, I immediately did a 50% w/c and turned down the heat. LMK what you guys think and how to treat it if it is. Thanx.....................