One whole fish is an impressive dish. And that's true whether you're hosting a dinner party, or bringing the fish for an evening of cooking together with friends.
In that case find out the best place in town to get fresh fish. If you don't already know, do some detective work and ask around. Ideally we'd all have an acquaintance, who actually fishes but that's pretty rare especially in cities. You can even call a restaurant with a good reputation for fresh fish dishes and see if they'll help you find a reliable fishmonger.
When you find the best fishmonger in town, ask them for the best ways to prepare a whole fish.