Cut the fish into pieces (according to your taste), it can be cubes, sticks, slices. Place the fish in a bowl where you will marinate.
Pour with lime juice and let stand for about 5 minutes, then pour over with lemon and orange juice.
Cut the onion thinly, mash it a little with your hands.
Cut the tomatoes into cubes and the chili.
Transfer all the ingredients to the dish with the fish, salt and pepper to taste and mix. Let it brew for 15 minutes. Cut the avocado into slices (to your liking).
Put ceviche on avocado and enjoy this unrivaled taste.