As for fish appearances, I definitely love the look of catfish. There was a pond by my grandparents' house that had catfish, and my family and I used to go to that pond and feed them bread crumbs when I was younger. So thinking about that is nostalgic for me.
And food-wise, I've gotta go with salmon. At first I didn't want to try it, but I'm glad I did, because it's actually really freakin' good^^