Wash the trout and pat dry, scratch the outside several times. Season the inside and outside with lemon juice, salt and pepper.
Mix the butter, garlic, salt, pepper and tarragon together. Fill the trout in the cracks on the outside and inside.
Place the trout in a buttered ovenproof dish and bake for 15-18 minutes in the lower part of the oven preheated to 200 ° C. The fish are done when the dorsal fins can be easily removed.