But I'd wager to bet that the younger GC need more calories per pound than the older ones (growing, swimming more vigorously, maybe trying to avoid predators, etc.)
I tend to think of young GC just like teenagers, a teenager will eat more food per pound of body weight than a 70 year old will.
Managing a pond is about controlling the biomass in the pond, and getting to work the most effeciently.
If a 30# 20 year old GC will control the weeds, why not replace it with a 10#, 4 year old fish that eats the same amount of weeds? That leaves 20# of biomass that you can have in reserve for the other fish to grow (or as a buffer against an O2 crash), or utilize it with other, possibly more desireable fish in the pond.
