Assessment 2: Purpose of plant material
If you find a food that has NO animal protein, therefore no fish protein, AND it also has TWO plant proteins, then the manufacturer is trying to get cheaper plant ingredients to do what fishmeal should be doing. And Koi feeding results will be mediocre at best. However, if you find a food with FISH MEAL as the first ingredient and THEN wheat germ meal or similar, they are using the plant ingredient for protein AND energy, letting the fishmeal carry the bulk of the protein requirement, which is as it should be. There will be some plant protein in most foods. It’s used as a helper, dual-purpose ingredient and it’s not to be eschewed.
Wheat flour may be used to keep a high protein pellet or food stick “stuck together” like a glue.