I've been shifting between being a lacto-ovo vegetarian and also eating fish for ten years, something. I don't remember exactly how long ago it was, since I became a vegetarian, but it was about that long ago... since a bit over a year back, I have given up eating fish, forever, as well. This is mostly due to the fact that the seas are being fished so much they are being emptied, and I could never be a part of this coming event that will lead to catastrophical consequences. Never got to test sushi, though... too bad. Well, I don't want tapeworms in my stomach, anyway.
Another reason to be vegetarian, aside from being healthier, is that you are far less likely to get infected by the incurable, mysterious and horrifying disease Bovine spongiform encephalopathy (BSE), then. Of course, in my case, it won't matter, even if I get infected, now, since I don't want to live a long life, anyway; the incubation period is ten to thirty years. Of course, I may have got it when I was a child, already... one never knows.
I've been considering becoming a complete vegetarian, and cease with milk and egg, sooner or later, as well, but I will see about that...