for me, being a pescatarian started because i was having digestive problems and couldn't stomach - literally - meat and foul anymore. fish didn't seem to bother me and so i kept eating it. now, i'm mostly a vegetarian, but on occasion i do still eat fish (it makes going to restaurants easier and i really do love my sushi) and though all of these dietary changes were brought about by health concerns, over the years in learning more about the ethics of it all, i am most concerned with the environmental impact of factory farming. big fishing is certainly also a major environmental problem, so i haven't exactly reconciled that yet. i feel like the moderation i exercise is probably helpful in not contributing too much to it, and the fact that i frequent farmers' markets and try to buy local as much as i can might offset that somewhat. in terms of killing animals and the ethics of that, i don't know what to tell you. i know no matter what i see killed, it doesn't make me feel too good - fish included, though it is admittedly easier to eat some sushi or piece of baked salmon because it doesn't look as animal as, for example, a chicken leg.