Clean the red snapper, remove scales but leaves the head and tail.
Slit the underside of the fish and remove the backbone, this will create a cavity; set aside.
Discard the shells of the mussels and clams and devein the shrimp set aside.
Heat oil in a pan and saute onion and garlic until crisp. Add the remaining vegetables. Add the mussels, clams and shrimps. Stir fry
Add the fish stock and season with salt and pepper. Cook some more until the liquid has reduced. Stuff his mixture into the red snapper cavity.
Wrap the red snapper in banana leaves and steam. ( alternatively, you can also use the oven and bake the red snapper in moderate heat if streaming is not desired).