Should water temp change as fish grow?

If you divide a fish's lifecyle into three phasees, fry, juvenille, and mature, will you get more optimum growth (i.e. less disease, faster weight gain) if you use a different temperature of the water for each phase of life?  Should the temp of the water for fry be a little warmer, when they are doing basic growing, and maybe a little lower, when they are mature, perhaps making them a little less active?