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How To Clean Tuna

Here is an in-depth instructional and guide into the ways of cleaning a raw tuna fish from washing it, to steps on how to fillet it, then how to store it and what to do once you catch it.

A pair of hands washing the raw tuna fish under the faucet.

A perfect tuna steak would make any person happy, a beautiful tasting fish that is also healthy. It is great buying already cut fillets from the store, but it is even more exciting to catch and fillet your own tuna. It is helpful to learn the skills needed to fillet a tuna correctly

Gut the tuna fish by making a small circular incision at its anus to remove the entrails; this will help preserve the prized belly meat. Once gutted, you can cool it in ice or fillet the fish. Fillet the fish, discard the carcass and remove the skin, cut it into steaks of desired size and thickness.

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How To Clean Tuna Fish?

Below are methods that can be followed to gut and fillet your fish the correct way to prepare it.

Gutting Your Tuna

This is a close look at a man slicing up the large tuna fish into chunks.

Before you start filleting your tuna, you will first need to gut it; this means removing all the fish’s insides. It is pretty easy to do this; most people will make an incision across the belly and pull the insides out. Although many people use this, some fishermen prefer to make a smaller circular incision in the anus of the fish to pull out the entrails.

The reason for doing this is to preserve the belly meat as much as possible as this is a special section of the fish meat. 

If you are not planning on filleting the fish straight away, it is important to cool it down quickly to avoid spoilage. Burry the fish in ice or place it in saltwater ice slush to cool it down.

Filleting A Tuna

  1. With a knife cut behind the head/gill area at a 45-degree angle till you hit the spine, cut as close to the head as possible to save as much of the meat as you can.
A pair of hands cleaning the tuna fish of its scales and fins.
  • Cut along the backbone of the tuna about an inch or two deep from the head to the tail.
  • Cut along the belly of the fish 2 inches deep, just as you did on the dorsal side of the fish. Cut from where you ended along the backbone at the tail and cut towards the gills.
  • Continue slicing the fish across the backbone and belly, making the cuts deeper on the tuna. Repeat these above steps on the other side of the fish.
This is a close look at a man filleting a large tuna tail on a concrete counter.
  • Once both sides have been sliced, continue cutting deeper around the fish you have already cut, use the bones as a guide until you reach the spine. Cut a hole on the tail-end of the fillet for your finger to poke through; this will help you hold it easily while cutting. Repeat on the other side of the fish by leaving the first cut side of the fish meat intact at the spine makes it easier to slice the uncut side.
  • Once both sides are done, the meat should only be connected at the top of the fish’s spine. Grab the fish with your finger where you inserted a hole, hold the fillet up and slice the connection at the fish’s head.
  • If there is still meat above the spine, use it to make sushi. Once the meat has been removed, the carcass can be discarded.
  • On the meat, remove the rib section by slicing at an angle to preserve as much meat as possible.
  • Your fillets have a line of dark meat and bone down the center across the length of the fish. Grab the fish at the finger hole, slice down the meat through the skin on the other side on both sides of the bone. This will help you hold the fish as you remove the largest portion of the fish’s bloodline and the bones.

Remove the skin from the meat by placing the fish skin down and running the blade between the meat and skin. With a larger fish, you can remove the skin from a 10-inch chunk of meat at a time. 

A man is filleting a small tuna fish on a boat.

You will find a concave dark section of meat on two of the loins; this section is very fishy and oily. Remove it by thinly trimming the fish till you reach the lighter meat.

Once the sections of fish meat are ready, you can slice them into steaks of your desired size and thickness. 

This method can be used for most large fish species. If you would like to detach the fillets as smaller pieces, then cut down the fish’s lateral line along with the bones of the fish on either side of this bone, slice the already made cuts on the backbone and belly using the bones as a guide till reaching the spine.

Slice the fish on both sides, and once done, finish by slicing the connection at the tuna’s head to detach the fillets.

Storing The Tuna

A chef putting the raw tuna in an ice bucket container.

If you do not want to cook the tuna straight away, place it in the fridge or pack it on ice. Ensure that the fish does not come into contact with the ice or is left open in the refrigerator; place the fish in zip lock bags until you are ready to cook it.

Avoid storing the fish in water where it is fully exposed, as this will hydrate the flesh that can leach the flavor and spoil the texture of the meat. If storing the fish longer than two days, make sure you store it correctly in the freezer to prevent spoilage.

What To Do Once You Catch Your Tuna?

This is a big tuna tail in a cooking pot.

It is also important to know what to do once you catch the tuna from the ocean because it can impact the quality of the meat. Once you catch the tuna, you have to let it revive; this is because they have a high metabolic rate and once caught, they are exhausted from the fight.

Reviving means allowing the fish to rest before killing it; there is a large buildup of lactic acid, which can spoil the quality of the meat if the fish is killed too early. You can let the fish revive by tying a rope around its tail and anchor the rope to the boat while re-hooking it in the mouth. Place the fish in the seawater next to the boat; allowing it to swim slowly helps it rest and lower the lactic acid buildup.

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