If your trout seems or smells fishy, you can bathe it in milk ahead of cooking for 30 or so minutes.

Fry diced onion in butter until onion is soft. Mix with pre made rice.

Dry inside of fish, spice internal cavity. Fill with rice mixture.

Wrap stuffed trout in a tinfoil pocket and bake at 350F until you can smell the fish in your home, approximately 20 minutes. Then check for doneness and continue cooking if needed.