It's very dramatic to say we all suggest your fish will die because of their diet. Drama's fun and straw man arguments are effective.
But your fish can stay alive and still eat a third rate diet, and that's not the goal of any aquarist I've met when they look at their fish. There's a multi-million dollar industry designing fish foods, and while I don't buy all their claims either, and have no brand loyalties when I do feed prepared foods (I cultivate live foods as staples for my fish, based on their dietary needs), I do buy their research. There's big money in aquaculture, and not a cow in sight.
if you dissect them (you're right about that at least, that kills them...) you won't find fatty deposits. They are unable to digest mammal fats and most of the meat passes right through, providing no nutrition. They'll pull some from the leaner bits, and they should survive. Give them enough, and they'll look good, though the fat will go into the water.
As is often the case in your postings, you're doing something from back in the days of that old fraudster Herbert Axelrod. 50 years ago, it was an experiment. It failed, and people went looking for better ideas. They found them.
Raw meat moved to heart meat by the 1960s, then as transportation networks developed, fresh fish (easily digested by other fish) replaced heart meat in the homemade recipes. Shrimp is now sometimes used when it's on sale, and white fish flesh (not as oily as say salmon) is a great idea for fish like discus. A lot of aquarists make their own foods - I have a stick blender out in a drawer in the fish area, and it has some kilometres on it. I've moved away from keeping Cichlids large enough to profit from such foods, but fish, shrimp, pureed carrots, mild paprika, pureed peas, gelatin to bind - those old recipes work very well.
They are old recipes though. You are one of the last holdouts with an approach tried and rejected when people were waiting for the newest Beatles record to come out. You give really contrarian advice, and it worries me that new members will think you are offering a healthy alternative for your fish.
Oh, for the younger members - Axelrod was the head of a fish and pet publishing empire. He was prone to guesses about this then fairly new hobby, and published info at a prodigious rate, with very little time to test it. Later in life, he ended up in jail for fraud. He was a spectacular self promoter who never let the truth get in the way of selling a book or magazine.