leaving my 75 gallon in the care of a non fish keeper for a week during christmas break. total of 10 dead fish, my angel pair was the worst of the loss. he didn't notice the evaporation, and the overflow eventually stopped, so no circulation, and no even heat distribution, so almost every fish had fin rot, ich, body fungus, and whatever else. The whole time he was saying everything's fine.... I guess he didn't notice. He won't watch the fish again.