i just changed the water in my tank, and my Flame Angel, started laying on his side in my tank, i put him in another tank, and he was fine, do u know if anything is wrong with the tank, it is 73 degrees farenheight, all the nitrite, nitrate, amonia, hardness, salt, ph level, and alkalinity are fine. is there any thing wrong with him, or do Flame Angels swim on there sides at night??? all the other fish were fine, after the water change.