[quote=Retired on 40]
This is much better weight gain than from natural food like insects & small fish, however. Fish must chase them down, using up energy, and besides they are mostly water.
Our member Jim Wetzel once said that the best gains he had witnessed was from dehydrated fish. I find this very easy to entertain. Fish has everything inside it that a fish might need nutritionally.
Makes perfect sense. The best feed contains fish proteins, rather than from, say, feathers. I seem to recall taurine as a vital nutrient fish need.
What I'd love to see researched is whether there is a design hack in some fish to, under the right circumstances, adjust their diets to fit what is available. I don't mean merely eat what is available, like tigerfish in Africa going after low flying birds, but metabolic changes enabling them to benefit more from a diet that would normally be inadequate in key nutrients. Daphnia develop armor, helmets & spears in response to predators, cichlids change jaw size, anolis lizards develop a cecal valve, some seagulls develop an organ to rid themselves of excess salinity, so why not check it out?