Fish farms... diseased parasite ridden fish, excessive use of chemicals such as formaldehyde to combat said parasitic fish lice, the sludge thats building up at the bottom of the farm location impacting the localised area. Seen on the docu eating our way to extinction. Wild salmon? Never know what they gonna do! They wild lol
Actually it depends on where it's farmed. Norwegian farmed salmon is awful, Scottish farmed salmon is much better (and really hard to get in Europe due to Brxt)