BillD. says "I also read a lot that feeding fish pellets allows fish to have a nutritious meal without expending much energy. Don't fish need exercise too? Is it possible that fish that depend predominately on pellets for food are out of shape and not as healthy as fish that eat natural forage with only enough pellets to supplement their diet?"
Good points and observations. Current fish foods have been developed primarily to grow fish to a harvestable size ASAP and economically. We are thinking that a long term diet of these current fish foods are shortening the life span of the fishes especially when these fishes are overly obese. A similar physiology and health condition happens in humans.
Now the next 'frontier' for fish food manufacturers is to develop a fish food diet that is more healthy for growing trophy sport fish with longer life spans.
Examples of overfed, overweight fish. In the first link CecilB expresses concern that these 4 year old fish may not live to be 5 yrs old. Normal life span of brook trout is usually around 9 to sometimes 15 years. Note these brook trout are over weight males not females full of eggs.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Main=30443&Number=389386#Post389386http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=389629&page=1
