The internet is full of wannabe "experts" that are writing blogs for clicks and fame, but know nothing about chickens. Chickens are a fad right now, and the internet is reflecting that. Same goes for various local facebook chicken groups. A lot of myths and misinformation circulate out there. And a LOT of paranoia! I agree with those who said to use this forum instead. There are lots of people on here who have actual experience, and methods that they've tested over time. This site is the best chicken resource out there!
I'm another one of the big fans of flock raiser type of feeds. I use Purina Flock Raiser which is 20% protein and covers all my needs - growing chicks, laying hens, males, retired freeloaders. And I provide calcium on the side (unlimited supply of crushed eggshell, though oyster is fine too). Fish and soy are fine, and Purina is a large and trusted brand so I leave it up to them what they put in there. I'd rather them make use of byproducts from the fish industry that work for this purpose, than add them to a landfill and burden the environment further by creating a whole new pipeline for chicken feed protein. Chickens are scavengers, they don't need organic grass fed filet mignon for their protein needs.