I eat fish, but I'm fussy about it; I won't eat it unless I've caught it myself, or I know that it's either farmed or caught from a sustainable fishery. This is because I think the way humans have almost destroyed several marine environments by their abuse of fisheries is inexcusable.
I don't eat fish fingers, fish sticks etc. but that's just because the other things they put in them (besides the fish) are things I try to keep out of my body as much as I can (ie trans fats.) I avoid most highly processed foods.
I'm fussy about my diet in general though; I'm not vegetarian, but I will not eat factory-farmed pork (cruel to pigs), broiler chickens (cruel to chooks), feedlot beef (cruel to cows and an outrageous waste of grain that humans need) or cage eggs (cruel to chooks). Fortunately there are free-range egg farms, chicken farms and piggeries in my area, so getting humanely-raised meat isn't difficult. I will vouch for the taste of it over factory-farmed meat - it is much, much nicer.