I'm not pescatarian, though I could be quite happily if it wasn't for DH and his love of meat. As it is, I have avocado with prawns for breakfast most days - and a small dash of Heinz Saucy Sauce (like Marie Rose, really). Lunch could be tinned sardines on toast, or a tinned tuna or salmon mayo sandwich, with salad veg.
Now and then I make Delia's Shallow-fried Fish, using whatever white fish I have to hand. Salmon and broccoli pasta is another favourite, then there's smoked salmon and scrambled eggs on toast, or baked salmon with a mustard and honey glaze. Homemade fish fingers are easy; just dip white fish gougons into flour, then egg, and finally breadcrumbs, and bake in the oven until done. Kedgereee using smoked haddock, cod or coley is good, too.
Salade Niçoise is a favourite, if I ever get my hands on fresh tuna, though I also like fresh tuna steaks, just seared until done on the outside and still pink in the middle.
Depending on the fish I have (I buy in bulk from an online fishmonger), I might have pan-fried lemon or black sole, or sea bass, or (if on a budget) whiting, just cooked in a little butter with lemon squeezed over. Also plaice the same way!
Fish pie is another option, or fish poached in milk with Parmesan. Don't forget the various fish patés available - nice for a snack on crackers or toast. Then there's fish cakes, or Thai-style crab cakes. Fish is so versatile. Hope that helps a bit :)