I always cook fish on the grill - year round! We live near the shore, and DH fishes alot. Plus, I grew up around fishermen at a marina, so we had lots of (free) fresh fish.
Most fish is good on the grill with garlic and lemon.
I also make stripped bass (stripper) on the grill. If you don't have access to this fish, as it is not usually commercially sold, you could use any thick white fish. I use one of those Reynolds foil bags, slice onions, peppers, tomatoes (or use salsa) and garlic, tuck it into the bag with the fish and throw it on the grill for about 15 minutes - remember to flip it over. Then you have a very flavorful meal.
Tuna is great rubbed with rosemary, thyme, garlic, parsley, lemon zest and olive oil, then grilled. We try to get ahi quality tuna, so we can enjoy it rare- to medium-rare.
I have great salmon recipes, one with a citrus tarragon marinade, one with a brown sugar and mustard glaze. If you are interested, I will post the recipes.
One baked fluke or flounder recipe I have is very easy:
1.5 lbs. of flounder
1 chopped onion
6 T. butter (I use less)
1/2 tsp. salt
2T. lemon juice
3 T. chopped parsley
pinch of thyme
Heat oven to 350. Melt butter in a saucepan over low heat, stir in lemon juice, salt, onion, parsley and thyma. Cover bottom of the baking dish with a thin layer of this sauce, place fillets in the dish, and top with the remaining sauce. Bake about 15 minutes, or until done when tested with a fork.
Good luck!