For me, the considerable environmental issues aside, the problem with farmed fish is that it simply doesn't taste nearly as good as the wild-caught versions.
Take salmon for instance. In a lifetime of preparing and then eating several portions of salmon per week, I've noticed that the farmed salmon are pretty much always:
-Very pale pink color, as though the animal was unhealthy (sometimes stores even add red food dye to cover this up)
-Weak and mushy flesh, even when fresh; healthy salmon flesh is muscled and springy, it isn't naturally slimy and it holds its shape
-Weak flavor that seems to be missing a lot of the more robust flavor notes entirely
-Thinner or nearly-nonexistent layer of fat between the flesh and the scales (contributes to less flavor overall and removes a lot of the umami); the same problem also applies to the thin bands of fat between the rows of muscle in the filet itself
-Skin/scales slightly disintegrate or fleck away at a touch instead of remaining intact
I don't even bother buying it even if it's significantly cheaper.
I can't imagine that the nutrient content is the same as the wild-caught fish. And based on the sickly look and taste of the meat, it's also very hard to believe that the farmed fish live a life that they find to be pleasant, to the extent such a thing is possible.
I eat plenty of farmed salmon (Atlantic salmon) because they are the default in grocery stores here and the few times I went out of my way to buy wild caught salmon I find that they are way worse. The first time I bought sockeye salmon not king salmon which was not fatty at all. The second time I bought king salmon shipped straight from Alaska and the flavor still disappointed. It's everything you say about farmed salmon: weak flesh, weak flavor, pale pink color. I'm starting to think I was scammed.
> the problem with farmed fish is that it simply doesn't taste nearly as good as the wild-caught versions.
I eat wild-caught salmon every day (as part of https://srid.ca/carnivore-diet) and can totally confirm this. Farmed salmon's taste is very off-putting. I noticed this only after switching to wild salmon for a few weeks.
A nice steamed white fish is pretty indistinguishable for me. But again I'm not a fresh fish enthusiast, and ultimately aquaculture makes adequate inputs for fish products like fish balls or fish pattys.
Arctic char and trout tend to taste more like their wild counterparts than salmon since they're raised on smaller, less industrialized farms. Many restaurants actually prefer Ora King salmon over regular king salmon due to the consistency.
Wild-caught salmon is pink because of the krill they eat, so in a way it’s also a dye. Farmed salmon definitely has coloring added to get this effect, but otherwise the flesh itself isn’t naturally pink.