What other fish do you recommend?
are they farmable on industrial scale to feed humanity?
For every 1 kg of salmon waten by a person 5-10 KG of anchovy or other fish is eaten by salmon.
I am not expert, I am just speculating that if you dig into details, picture can be very different.
I regularly go to the fish market, small seafood like anchovi and shrimp can be bought 4 times cheaper than salmon.