Cut the fish into fillets, remove the bones and skin. Season with salt and pepper on both sides.
Pour vegetable oil into a frying pan and heat it well. Roll the fish in flour and fry on all sides until golden brown.
Cut the onion into half rings. When the fish is ready, remove it from the pan and send the onion there, add lemon juice and fry for 5 minutes, stirring occasionally.
Place the fish on a large plate and place the onion on top. Very tender and delicious fish is ready. Enjoy your meal!