I cook a lot of fish.. but mostly just salted/peppered and grilled. Or just raw. The one recipe that's always popular, though, is halibut breaded with crushed Tostitos or Doritos, fried and served with homemade salsa mexicana. Any firm white fish is OK, but halibut is glorious. (The breading is as usual.. coat in flour, then egg, then the chips.)
Peppered tuna steak is always good, if you have the cash for/access to sashimi-quality tuna.. I oil the steaks a bit, coat heavily with cracked peppercorns, then sear the outer 1/8" of each side. I usually cube it and serve in (Japanese) soya sauce with a mound of wasabi. Other oily fish is good this way, too, but it has to be sashimi quality. Don't believe a word from the fishmonger at Sainsburys..
I'm weird about trout. Love it just after catching it, don't like it if it's older. So, I usually gut it and cook it right away. Pan fried in butter, lemon juice squeezed on as we eat it. Or blackened over a campfire, skewered on a stick. But hey, everything tastes better with sticks!