One of my rules is there are different ways to do things, no single, cosmic secret. I've watched a couple of his videos and can allow that what he does works for him, but he lost me long ago by making it sound like he has the secret to fishkeeping, that his is THE way to do it, and by dishing up his own gumbo of personal opinion and cherry picked 'facts'. For one thing what he's doing isn't new, just his take on "dirted," low maintenance tanks, which have been around forever and include the "Walstad method" and earlier 19th century concepts of creating a natural ecosystem, before there was powered filtration. Imo the whole "father fish" thing is half grandiloquence and half marketing malarkey for the sake of his youtube channel.
Father fish is some eccentric old guy who once owned a shop and wants you to think he has a cosmic secret. Diana Walstad is an author with a microbiology and research background, besides other credentials, who explains the science in easy to understand terms without the labored, rustic philosophy. One is a waste of my time, the other is worth reading to understand aquarium ecology, even if you don't intend doing a dirted tank.
...my opinion