Ikejime: How to Spike, Bleed and Ice a Fish You Will Eat

Ikejime is the Japanese way of killing a fish you plan to eat: a spike into the brain, a cut to bleed it, an optional wire down the spinal cord, then an ice slurry. Australia’s national code for recreational fishing names a brain spike and a firm knock on the head as the two preferred ways to kill a fish. Done within a minute of landing, it ends the struggle that burns through the muscle’s energy, so the flesh stiffens later and keeps longer.

Flathead flounder killed instantly with a cut to the hindbrain reached peak rigor at 48 hours in a Kyoto trial (2018, reported 2019). Flounder left to die on ice got there at 24.

What does ikejime do to the flesh?

A fish that fights and then suffocates spends its muscle’s energy store, ATP, and builds up lactic acid. When the ATP is gone, the muscle locks into rigor mortis and the slide toward spoilage speeds up. The spike stops the brain’s drive. Bleeding removes the blood that carries bacteria and off-flavors, and cold slows everything after.

That makes it worth doing for a fish you will keep and eat, most of all one eaten raw or a few days after the catch. Chef Dannel Krishnan told the Michelin Guide there “isn’t much difference” when he cooks a fish with or without it on the first day. “The difference comes in only in the third, fourth and fifth day of aging.”

It is never for a fish you will let go: catch and release is the opposite job.

What does ikejime mean, and what is shinkei jime?

Andrew Tsui of the Ike Jime Federation renders the word as “live killing” in FishTalk. The jime part comes from 締, “to tighten, to close” (Sushi-pedia). Wiktionary gives the English pronunciation as ee-kay-JEE-may; ikijime.com says it is pronounced “iki jimi.”

In Japan, ikejime is the umbrella word for killing a live fish on purpose to keep its quality. The spike step is nōjime, which Sushi-pedia glosses as “brain killing,” followed by the bleed. Shinkei jime (shinkei means nerve) adds the wire as a third step: a thin wire run down the canal above the backbone to destroy the spinal cord. In American usage “ikejime” often means the spike alone.

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What do you need?

• A spike. The agencies’ budget tool is an ice pick or a sharpened screwdriver. Brand spikes run from $19.99 (JYG Brain Spike) to $29 (AFTCO Ike Jime Spike).
• A wooden club, or a priest (a baton with a metal head), for the knock before or instead of the spike.
• A sharp knife for the gill cut.
• A wire, for shinkei jime. AFTCO’s Circuit Breaker, made with the Ike Jime Federation, runs from $29 for the 18-gauge striper-and-snapper size to $89 for a 50 in (127 cm) tuna wire. Johnny Jigs’ NeuroSpike wire tool is $35.99. No wire? Totos of Japanese Anglers’ Secrets used stainless rigging wire about 1 mm thick, sold in tackle stores.
• A bucket of water to bleed in, and a cooler with ice and water for the slurry.

Spending runs from about $20 for a spike alone to $49.99 for JYG’s Ikejime Pro Kit: spike, bleeding knife and wire. A screwdriver, a club and a bag of ice do the agencies’ version.

How do you spike a fish?

The kill, bleed and chill below follow Australia’s national code (through ikijime.com), RSPCA Australia and FAO. The consciousness check and the gill cut on both sides are SPCA New Zealand’s. The wire step is the one AFTCO and Maryland DNR describe.

1. Get ready before the fish lands. Have spike, knife and slurry ready, and keep the fish in the water or the net until the tool is in your hand. ikijime.com asks for the kill “preferably within a minute of it being caught.”
2. Choose: knock or spike. A firm blow just above the eyes with a club is, in ikijime.com’s words, “the easiest method of humane killing.” It advises a knock first on channel catfish, which have a strong skull. It says the same of large, energetic snapper, mahi-mahi, tuna and halibut. If the fish is still conscious, strike again.
3. Spike at the species point. Push the spike in quickly and firmly at the spot in the table below, then wiggle it side to side to destroy the brain. On offshore fish, Louisiana Sea Grant aims at the soft spot above the eyes at about a 30-degree angle.
4. Check the kill. The fins flare and the mouth gapes, then the body goes limp. Tilt the fish: an eye that rolls as you tilt it, or a gill cover still pumping, means it is conscious. The gill sign does not apply to tuna, which ram-ventilate: they swim to push water over the gills. Spike or strike again.
5. Bleed at once. Lift the gill cover and cut through the gill arches on both sides; on a big fish, cut a main artery, and on a tuna, cut under the pectoral fin. Hold it head down in water while the heart pumps: 5–10 minutes or until the flow stops (Louisiana Sea Grant), 10–15 for a small fish (FishTalk).
6. Run the wire, if you want shinkei jime. Cut down to the backbone at the tail, not through it, and find the small hole above the bone. Push the wire up the canal toward the head and work it back and forth until the twitching stops.
7. Chill in slurry. Mix at least one part ice to one part water; ikijime.com asks for two parts ice to one, and FAO calls four to one “the best slurry.” Keep it near 32 °F (0 °C) but never below, and add no salt. Louisiana Sea Grant takes a normal-size fish out within 2 hours.
8. Drain, bag and ice it. Bury the fish straight in ice, about 2 lb of ice per pound of fish. FDA’s guidance for any seafood is 40 °F (4 °C) or below, eaten within 2 days or frozen.

What should you see when it works?

A good spike makes the fish flare its fins and open its mouth, shudder, and go limp; the color may change. After that there is no eye roll when you tilt it and no gill movement. In a German trout study, those two signs disappeared when the brain stopped responding to light, so they are a fair field check. A heartbeat is not: the AVMA notes that a fish’s heart can keep contracting after brain death.

It is not always instant. In a 2025 study that read brain waves, manual and machine ikejime left every rainbow trout insensible within 2 minutes. But in the authors’ words, “neither reliably achieved immediate insensibility.” In hybrid striped bass of 1.1–2.1 kg (2.4–4.6 lb), about 25–43% stayed sensible after the spike. The authors’ advice: stun first. Knock a big, hard-headed fish before you spike it.

Whether a fish feels pain is contested, and do fish feel pain sets out both camps. What the same study measured is time: fish left to suffocate showed distress for up to 13–16 minutes.

Where is the brain? Spike points by species

A fish’s brain sits behind and above its eyes, and it is small. The rule of thumb: on a bass, trout or panfish it is 1–2 eye-widths back and about one above; on a walleye, striper, channel catfish or flounder it is about 3 back.

The table reads ikijime.com’s x-ray-matched diagrams. Side view: from the center of the eye to the center of the marker, in widths of the fish’s own eye. Top view: along the midline, back from the eyes. Use the side view on fish that lie flat on their side, the top view on round fish and flatfish.

The wire sizes are AFTCO’s (Johnny Jigs’ for mahi-mahi). AFTCO adds a landmark that works on any fish: the brain lies near where the top of the preoperculum, the curved bone between the eye and the gill cover, meets the lateral line. FAO puts it on a medium fish about 2 cm (¾ in) behind the eye, spiked diagonally from the right side.

Is ikejime worth it? What the studies measured

The measured gains are in stiffness and freshness over days, mostly from Japanese fisheries labs. Bass, walleye and catfish are not among the fish studied.

The K value is the Japanese freshness index. About 20% or less is the benchmark for eating fish raw, and 40% for cooking it. Both hindbrain-cut groups of Kyoto flounder were raw-grade at 30 hours. At 54 hours the wired fish read 30%, the cut-only fish 37%.

So is it worth it? For texture and keeping, the measurements say yes, and the gain shows after a day or more. The wire is the marginal step: it delayed rigor in yellowtail and sea bream but brought it on sooner in plaice. None of these studies measured taste.

Mistakes to avoid

• Missing the brain. A fish still moving its gills or rolling its eyes was missed: spike again or knock it at once.
• Bleeding without a stun. RSPCA Australia lists it as not humane. Bled alone, a fish can take more than 15 minutes to lose consciousness (The Fisherman).
• Skipping the slurry, or icing a trout alive. Slush cools a fish 4–5 times faster than ice alone (Louisiana Sea Grant). Straight into slurry can suit small warm-water fish, ikijime.com says, but it “may not be effective or suitable for large fish and/or cold-adapted species (e.g. trout).”
• Letting it die on a stringer or in a bucket. ikijime.com calls a slow death in air or a bucket “unacceptable”: it stresses the fish, lowers eating quality and shortens storage life. Keep it alive on a fishing stringer or kill it and ice it; pick one.
• Too cold, too long. FAO warns that partial freezing at −1 to −6 °C (30 to 21 °F) encourages spoilage, and a long soak bleaches red skin and clouds the eyes.

How old is ikejime, and is it legal to sell?

None of the sources here puts a date on the spike itself. The wire step is in Japanese fisheries papers from the mid-1990s. The “350 years” that circulates appears in a 2017 Michelin Guide article, which says such techniques “are said to have developed some 350 years ago” and cites no source.

The US milestone is Maryland’s Chapter 430 of 2025. It added Health-General §21-305(b)(7): a DNR-licensed fisherman who “harvests and processes finfish on a vessel by ikejime for direct sale to restaurants” needs no food-establishment license. Before it, Maryland DNR wrote, “only recreational fishermen can use the process in the state on their own catch.” The law permits ikejime; it requires nothing of anglers.

When is a knock and a bleed enough?

For a walleye or a bass headed for tonight’s pan, a club, a gill cut and a slurry do the agencies’ job; the wire buys days you will not use. Is bass good to eat and are pike good to eat cover which fish to keep.

A channel catfish gets the knock: ikijime.com says its skull is strong and a spike needs to be robust. Bluegill and crappie from summer water over 70 °F (21 °C) may go straight into slurry. For flatfish the spike and bleed are the sure gain; the wire hastened rigor in plaice. And a fish you mean to release gets none of this.

The basics hub has the rest of the handling fundamentals.

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