Fish can be farmed with low environmental impact and without antibiotics. What is lacking is domestic feed ingredients for fish feed that do not compete with our own food, and that suits the fish. Sweden has an advanced management of by-products, and the technology to process these by-products into other products.
Read the article in SLUs Knowledge bank (the content is in Swedish).
http://link.springer.com/article/10.1007/s10695-016-0297-0
Huyben D, Vidakovic A, Nyman A, Langeland M, Lundh T, Kiessling A. 2016. Effects of dietary yeast inclusion and acute stress on post-prandial whole blood profiles of dorsal aorta-cannulated rainbow trout. Fish Physiology and Biochemistry. DOI 10.1007/s10695-016-0297-0
Huyben D, Vidakovic A, Langeland M, Nyman A, Lundh T, Kiessling A. 2017. Effects of dietary yeast inclusion and acute stress on post-prandial plasma free amino acid profiles of dorsal aorta cannulated rainbow trout. Aquaculture Nutrition.