I know several professional fish nutritionists and fish physiologists who will disagree with several of your generalizations depending on which fish specie you are referring to and the nutritional needs of that specie. No doubt some of what you are saying is true but IMO it does not apply to all species and sizes of fish. I think nutrition requirements especially protein changes as the fish ages. A lot is yet to be learned about fish nutrition and the long term needs for each species for good health of each specie of fish.
I also will ask the same question as posed by Cecil: why do they make noticeably higher protein foods for fish fry and fingerlings? Is it just to make more money from uneducated fish growers?
I'm not trying to be contradictory, just asking questions and expressing some of what I've learned so far about fish nutrition.
One has to be careful to not wholeheartedly believe everything that is in print. Go to some professional meetings where research is presented and listen to the critical comments about the scientific methods used by some researchers. Faulty scientific method can lead to faulty biased conclusions that are put into print.
If your friends want to come on and discuss fish nutrition I welcome them. I would love for someone to tell me why a LMB and SMB need different foods. Oh but LMB eat bluegill and SMB eat crayfish. Its true they have adopted different hunting styles because of the habitat in which they are comfortable. Once the food goes down the gullet its all the same. At the end of the day it all comes down to biology. A food containing 40% P 11% F AND 20% Starch will grow them so close to the same rate that you won't notice the difference.
I don't object to raising protein to 50% for fry and juvies. The length of time that they are fed this food is so short that no harm is done. A diet high in protein and marine fat will produce fantastic growth rates. However the study that I posted and several others have shown very little difference in growth between 35% P and 55% P. My guess is the optimal protein percentage for growth is 40 - 45 percent.
If it were one study showing 35% protein worked as well as 55% protein food that might have a leg to stand on.
They are arguing because the studies in question are not in their best financial interest. Industry studies tend to favor the result of the client paying for the study. That's why studies done at universities hold more credibility. The study I linked was done for fish farmers in South Florida. They were losing abnormal percentages of their stock and didn't know why. They provided the fish and U of F did the study. They got the result they wanted on the 35% protein food but still had no idea why their fish were dying.
Can you imagine me going too one of these seminars and saying what I am saying here? What can I possibly gain from coming on here and telling you lies or half truths? Who benefits from a different fish food for every fish under the sun? It for sure ain't me.
You seem to think that I have read a few studies and formed some half-baked opinions. I can assure you that I have spent countless hours studying fish nutrition, fish studies and done testing on my own. All I can do is tell you what I have learned.
