- 1). Lift the gill plate with your fingers and insert a knife beneath the plate. Slit the gills with the knife until a steady stream of blood is produced. Repeat the process on the opposite side of the fish and allow the blood to drain for 10 minutes. Draining the blood leaves clean and edible meat.
- 2). Turn the fish onto the back and locate the ventricular opening at the base of the stomach. The opening is the only small hole on the belly of the fish. Make a shallow, 3-inch-long slit along the vent and stomach.
- 3). Reach inside the slit and hook the main intestine with your finger. Pull it out of the slit and cut the intestine with the knife.
- 4). Lift the gill plate and cut along the gill attachments. Completely separate the gills from the head with the knife and grab the gills with your hand. Pull the gills in one smooth motion, and the guts will follow through the opening.
- 5). Rinse the gutted cavity with cold water to remove all of the blood and matter. Place the fish on ice and fill the cavity with ice to cool and store the meat. Fillet or prepare the tuna as desired.
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