I don't watch many Aquarium channels, but here's the ones I'm subscribed to;
KingofDIY
AquariumCoop (and their 2nd channel Jimmy of Aquarium Coop)
Rachel O'Leary
L.R.Bretz's Aquatics
Flip Aquatics
Ted Judy
Greg Sage
There's also;
Corvus Oscen
Steenfott Aquatics
Steve Poland Cichlids
Greg Jones
It amazes me how many people have you-tube channels dedicated to keeping fish... and they mainly keep guppies. Nothing wrong with guppies, but these channels do not even go into line breeding, or selecting for traits. No these people have multiple tanks with colony breeding of guppies. And people send them money in "super chats" to explain how they keep them. My 5 year old has a better idea of how to keep guppies.