Breaking Down Half an Ahi Tuna

I just got this beautiful half ahi from a local fisherman friend. Today, I am going to show you how to break it down into usable portions with as little waste as possible. In the days to come, I will be posting recipes that use these portions. If this is your first time breaking down a large portion of fish like this it may seem a little intimidating. Just remember you get to eat your mistakes and with a little practice, you will be a pro in no time.

First, I started by skinning the tuna. The easiest way to do this is to start at the tail. Slide your knife between the skin and the meat. Once you get a small portion started, grab the skin with the opposite hand and pull the skin toward you as you push the knife forward into the fish. This part does take some practice, so be patient, if there is meat left on the skin it’s totally usable. When taking the skin off a fish sometimes a spot will get missed. Just take the point of the knife, slide it under and out one edge of the skin. Pull up on the skin while slicing forward through the meat until the skin is free.


To remove any leftover meat from the skin simply scrape the meat off with a spoon. When you have skinned the fish and scraped any leftover meat, discard the skin and wash your cutting board. This is an important step because there are usually scales left behind and the oils from the skin can impart an unpleasant flavor.

Next, we are going to remove the bloodline from the fish. This is the dark almost black portion. There is a small piece of meat left on the outside, so I am going to cut this off. Again, it doesn’t have to be perfect but you do want to remove any dark pieces that remain.

I like to look at the edge of the fish to get a better idea of where the bloodline is and how I’m going to cut it off. I start at one side and run my knife down the length of the fish between the meat and the bloodline in a smooth line. These cuts are not deep, maybe 1/4 to 1/2 inch. Then repeat this process until the bloodline has been removed. This process may take a little time, but I feel it’s the easiest way to remove the meat cleanly without a lot of waste. If you leave any meat on the bloodline or vice versa it can easily be trimmed off. The bloodline is edible, but it has a very strong flavor not everyone will like. I usually discard this portion. If you want to use it without eating it, you could use it for fishing bait or bury it under your plants for fertilizer in your garden.

In the first photo above you can see a white line of sinew that runs the length of the fish. The sinew also runs at an angle toward the bottom of the fish. This separates the fish into what I call the “eye” portion and the sinew portion. I remove this portion almost the same way as removing the bloodline. Starting at one end of the fish with the blade on the top of the white sinew line working my way down at an angle to the bottom of the fish. Once removed, I dice up and scrape (like the skin) the sinewy portions. The “eye” part of the tuna I will cut in half lengthwise and divide into blocks, fish and chip, and dice. Using any smaller or scrap pieces for the dice.

The portion of the fish above is the belly side of the tuna. It breaks down the same way as the one on the top of the page with one exception. On the sinewy side, there is a thin white membrane (sometimes with bones) that will need to be removed. This to me is probably the most difficult part. The membrane is thin and tears easily. It will require some patience. Start at one end sliding the tip of your knife under the membrane to loosen a small portion. Much like removing the skin, pull up on the membrane while sliding your knife across the meat to separate. If you leave meat on the membrane don’t worry just scrape the membrane with a spoon to remove the meat. I break down the “eye” portion as before making blocks and dice. The sinewy side of the belly has more fat and is ideal for fish and chip portions and scraping. To make fish and chip portions I simply slice the fish at an angle into about 3 1/2 inch long pieces with the widest part no more than an inch wide.

This is the ahi completely broken down. Starting at the top left going clockwise we have scrapings, fish and chip portions, blocks, and dice. The scrapings I use for ahi sliders. Fish and chip portions for, of course, beer battered fish. Blocks for blackened ahi and confit ahi. The dice for fried poke bowls. I hope this made breaking down an ahi simpler for you. Remember this will take practice and mistakes taste just as good!


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