I read that Tilapia for example contains Omega 6 fats (Omega 3 is what we are advised to consume) due to their feed consisting of corn! Some claim it was akin to eating a hotdog. Most Tilapia is farmed in China, so lord only knows what practices are carried out there from production to slaughter.
I have since stopped buying this fish. I didn't eat much of it anyway.
Most Salmon - approximately 70% is farmed now and they have caused controversy like disease and GM salmon (that grow faster) for example. And in creating 1 pound of farmed salmon more than 3 pounds of wild fish meal is consumed.
Eating at restaurants - my guess is they wouldn't have a clue if the fish was farmed or not.
Costco does label if the fish is wild or farmed. I am not sure if the 'wild' means something like off-shore cultivation" when the cages are placed in the sea or what we imagine a fish farm to be like.
Well where are the best places to buy non farmed fish?