Hi, I am a vegetarian that eats fish sometimes, I have been a vegetarian my whole life. I don't eat fish much but when I do I eat barrimundi or salmon, you can buy salmon in the can as well, and debone it and have a salmon and avacado wholemeal sandwich with no butter or margarine, it is very healthy and good for you.
Also I like to cook brown rice and mix the salmon through with it and eat it like that with steamed vegies on the side. If you like to cook it whole, cook it in foil in the oven and squeeze lemon over it and dice garlic over it and a bit of pepper and that is it, and steam some vegies on the side, very good for you
That is how I eat fish and also you can cook pototao and mix salmon with it and some wholemeal breadcrumbs and an egg, and some herbs, and put them in balls, and line a baking tray with foil and bake them, really nice as well, I did them for a christmas party with my family and they didn't stop raving about them,they really like them and ate them all
Don't force yourself, just eat it once a week or fortnight that is fine, eating legumes for protein is the perfect protein for people as it is not too much protein, and very good for you when you don't want to eat fish.