1. Gut and clean the fish, then cut into medium sized pieces. Bring a pot of water to boil, then boil the fish for about 5 - 10 minutes until fully cooked.
2. Remove the fish from the water, drain fully, and leave to cool.
3. Once the fish is cool, carefully take off the skin and debone all the meat from the fish, and flake the fish in your fingers so it's almost like deboned minced fish. Discard the bones and skin.
4. Set aside the fish for later.