Well, it helps prevent depletion of wild fish stocks. I know with some kinds of fish farming, waste is a big issue, but with others, it's not. Frankly, the only salmon I like is farmed, so I'm all for that.
I'm not a big fan of fish in general. The only kind I do like is the fresh caught perch hubby brings home in the summer. I have heard that farmed is supposed to be less "fishy" but nothing I have had compares to fresh.