Have blender container cold. Chill it by putting into freezer for 10 minutes, or set it in ice cubes until it is cold.
Dry fillets on paper towels and then cut into pieces. Put into blender container. Add 3 whites, one at a time, blending after each, then a fourth if mixture does not look wet. Add salt and pepper and blend to a thick paste. Run rubber spatula down sides of blender container to give air to the mixture so it will blend and not just whirl in the middle. (Foods must breathe while they are being blended.)
When thick, start adding crème, a tablespoon at a time, on low speed. The amount of moisture in the fish will determine how much crème it will hold. It may be 3tablespoons, and it may be 5. Too little crème results in dry quenelles; too much causes the quenelles to disintegrate into the water. Test the mixture, then adjust the crème, egg whites, or seasonings. If perfect leave it alone.
Shape quenelles with two spoons. Poach in simmering salted water. Drain and use in sauces or serve with Quenelle sauce. Or add ½cup shredded crab, lobster, or shrimp to the sauce and serve as first course in coquille (shells).