I have been summoned! Wahahahaahahahahaa! errr ummm...
Ok, my advice for what its worth? Ignore almost evertything on the bag. The most important things on a bag of feed are:
A)
The mill date. It doesn't matter how good the feed once was, if its value has been degraded by oxidation or its been taken over by a colony of mold, mildew, etc. Mites, roaches and the rest making a home in it isn't quite so bad, as they have nutritional value, but because no proces s in nature is 100% efficient, they have less total value than the contents of the bag that they ate (plus whatever they were eating before they got into the bag.)
B) The
guaranteed nutritional label. Your birds and your needs will determine what the optimum mix of vitamins, minerals, fiber, fat, and amino acids will be (many use protein % as a stand in for amino acids - they aren't far wrong, but they aren't right, either.).
and I'll use your fish meal question to illustrate why. Fish meal, or any animal protein meal (menhaden [fish] meal, porcine blood meal, crab meal, etc) is a high protein %, moderate fat, high (relative) cost suppliment used to compensate for the lower nutritional value of much lower cost (usually grains) ingredients. One of the most, if not the most, important limiting amino acids in a chicken's diet is Methionine. Metchionine is literally the first building block of protien creation. Its used to make strong connective tissues - skin, tendons, and the digestive system primarily, but its a component of most everything else.
Without enough methionine, the rest of the protein components in the feed are wasted - because without that first building block, the rest can't be used - like a train with no engine. Its so critical, in fact, that even feeds bearing the "organic" label can contain some amount of synthetic Met.
Fish meal is an EXCELLENT source of Met, which is good, because there are no natural plant sources which, in their raw state, can meet the minimum needs of a modern chicken for optimum growth and productivity. Most of the literature suggests rates of inclusion up to 10% are ok, and Justin Rhodes' well respected "make at home chicken feed" contains 10% fish meal without apparent feedback of "fishy flavor" from those who use it. However,
@Lazy J Farms Feed & Hay does feed science for a living and has advised that the industry tries to keep fish meal at 5% or less. I trust that opinion. Taste is HIGHLY subjective, and fish meal is a product whose composition can vary wildly. Fish meal made from sardines or salmon is much different from fish meal made from tilapia or catfish. Don't use the fish meal found in the garden center, use fish meal with its own nutritional label. Or a commercial feed that has sourced its own fish meal.
How much Met do you want? That depends on the age of your birds, your needs for your birds, your budget, and your expectations. The old numbers generally agreed that Met levels of 0.3% were adequate for adult layers under commercial conditions. Hatchlings and juveniles need more, and more recent studies have suggested that modern production layers benefit from higher met levels, as do meat birds (much higher met levels) to support their very high growth rates.
Anyhow, that's a high level overview, I hope it provides a starting point for you.
and this is
my general generic feed recommendation.
