Ah come on it's not just asceticism. Anchovies, sardines, herring, mackerel and other small fish populations are currently being decimated, and 99% of the catch goes to producing... farmed meat, including salmon. Even if they've solved pollution & disease, if you're putting in 2lbs of unsustainably caught wild fish and getting out 1lb of farmed fish, you don't have a sustainable model.

It's kind of tragically ironic- those small fish are incredibly healthy food & quite inexpensive.