Just curious as to what temp you keep your tank at? Does a degree or two make any difference (ie 78 vs 80)? Do you note your GSP's seem "happier" at a given temp?
Is it possible different fish like different temps? I know this sounds sort of silly since its such a small difference but Dragon kept hanging out hiding all the time, I turned the temp down from 80 to 79 last night and he's been out swimming, curious, and bright as can be all morning so far.
Its possible that such a minor temp difference could be due to differences in thermometer readings, not actual temperature differences. When we buy a thermometer, we assume that it reads properly. When you buy a dozen and leave them all out and then look at them, you realize there can be significant differences in the readings at the same temp. I bought a dozen nice aluminum cased pocket-clip field thermometers and the range of readings was 4 degrees. I now check my thermometers against a calibrated digital unit.