Very useful, thank you, Andy. I already keep my angels at 78. I think the breeder uses 80. I tend to keep most ofmy fish below average. This came about because the guy who sold me my first 90G that came will a mixed cichlid/syno cat community never used tank heaters. He kept his house at 70f, year round. I learned this is not unusual. We found 3 little fish in the sump tank. Same thing continues. Most grow up to be magnificent Blue Dragon Peacocks