I'm strict vegetarian and never have fish. I eat ground flax and take an omega oils supplement from vegan sources. You don't HAVE to eat fish to get those things they're talking about, even if you're not vegetarian. There are many other options, if you don't often eat fish or don't like fish
I LOVE fish but, because of time/money issues and stress, I always have a hard time incorporating it into my diet. I always seem to go through the motions with my meals, even if I really want a good tilapia filet.