Tomozuri
Method · Last reviewed 2026-08-13
A Japanese river method that catches a fish by using another fish of the same species to make it angry. There is nothing else quite like it, and it exists because of one specific behaviour of one specific animal.
Tomozuri — literally 'friend fishing' — is the principal Japanese method for ayu, and it works by exploiting territorial aggression rather than feeding. A live ayu is harnessed to a line, with a small treble hanging behind its tail, and swum into water occupied by a wild ayu. The resident attacks the intruder to drive it off its feeding stone, and in doing so is foul-hooked by the trailing hook. The fish just caught is then used as the next decoy.
IT IS BUILT ENTIRELY ON THE ANIMAL'S BIOLOGY. Ayu spend their river phase grazing algae from the surfaces of stones, and a productive stone supports one fish. So an adult ayu holds and defends a territory around its stone against other ayu, aggressively and continuously, and does not defend it against anything else. That single behaviour is the whole method — no bait, no imitation, no feeding response, and no other quarry in this catalogue is fished this way.
THE TACKLE IS EXTREME AND FOLLOWS FROM THE PROBLEM. Rods are very long — eight to ten metres is ordinary — because the decoy has to be manoeuvred precisely into a specific patch of water at distance without the angler entering it and without the line dragging. They are extraordinarily light for their length, because they are held out over the river for hours. The line is fine, the harness that holds the decoy is a small and specific arrangement of hooks and rings, and the whole outfit is among the most specialised in freshwater fishing anywhere.
IT IS ALSO A COMPETITIVE SPORT WITH REAL STANDING IN JAPAN. Ayu tournaments are fished seriously, tackle is developed for them at considerable expense, and the season's opening on well-known rivers is an event. The fishery is generally managed by river cooperatives with permits, defined seasons and stocking programmes — arrangements that vary by river and are the local authority's to state rather than this record's.
What it is
A Japanese river method for ayu in which a live ayu, harnessed and trailing a small treble, is swum into a wild ayu's feeding territory. The resident attacks the intruder to expel it and is hooked in the process. The captured fish becomes the next decoy.
How it works
The decoy is held in a nose ring and a light harness that allows it to swim more or less naturally, with a short trailing hook — the kakebari — hanging behind and below the tail. The angler steers it with the long rod, working it upstream and across into the water a resident fish is holding.
The attack is a ram or a bite aimed at driving the intruder away from the stone, delivered at speed and from behind or below, and the attacking fish makes contact with the trailing hook in the course of it. The hooking is therefore incidental to the aggression rather than to a feeding attempt, which is why the hook is where it is.
Managing the decoy is the skill. A tired, frightened or badly harnessed decoy sits still, drifts downstream and provokes nothing; a fresh one swims, holds its position in current and looks like a genuine intruder. The convention of immediately swapping to the freshly caught wild fish exists for this reason — the newest fish is the strongest swimmer and works the hardest.
Reading the water is the other half. A good ayu stone is identifiable: the right size, the right depth, the right current speed, and the grazing marks the fish leave on the algae are visible to somebody who knows to look for them.
What it is for
It catches a fish that essentially cannot be caught otherwise. Ayu graze algae and will not take a bait or a lure in any reliable way, so a feeding-based method does not work on them. Tomozuri is the answer to a quarry whose feeding behaviour is unfishable and whose territorial behaviour is not.
Setting it up
- The decoy must swim properly. Everything else in the method is downstream of that.
- Rod length is dictated by the need to place the decoy at distance without the angler disturbing the water, not by the size of the fish.
- The harness is arranged so the trailing hook sits where an attacking fish will meet it, and adjusting that position is the fine tuning of the method.
- Swap to a freshly caught wild fish as the decoy whenever possible, because it is the strongest swimmer available.
- Establish the river's cooperative permit, season and gear rules first, which in Japan are specific to each river.
Advantages
- It catches a species that is not reliably catchable by any feeding-based method.
- It is precise — a single identified fish on a single identified stone can be targeted.
- It is self-sustaining through a session: each fish caught supplies the next decoy.
Limitations
- It requires a live ayu to begin with, bought or caught, and a way of keeping it alive.
- The tackle is highly specialised, expensive and useful for nothing else.
- It works only where ayu are holding feeding territories, which is a specific season and a specific water type.
- It uses a live fish as gear, which is a genuine welfare question and is illegal or restricted in a number of countries outside Japan.
Conditions
Clear, fast, stony rivers in the ayu's summer river phase, where fish have established grazing territories. It does not work before territories are established, in coloured or spate water where the decoy cannot be seen or controlled, or in slow deep sections where the algae-covered stones are not.
Common mistakes
- Fishing an exhausted decoy. A decoy that has stopped swimming has stopped being a method.
- Wading through the water about to be fished, which moves the resident fish off the stone.
- Ignoring the stones and fishing the water generally, when the method is directed at an individual fish in an individual place.
Terms you will meet
- Tomozuri (友釣り)
- 'Friend fishing' — the method's Japanese name, from the use of one ayu to catch another.
- Otori
- The decoy fish itself.
- Kakebari
- The small trailing treble that hangs behind the decoy and hooks the attacking fish.
- Hana-kan
- The nose ring through which the decoy is held, allowing it to swim while remaining under the angler's control.
The welfare question, stated rather than resolved
Tomozuri uses a live fish as an item of gear, and it is worth saying so plainly rather than leaving it implicit in a description of a harness.
Within Japan the practice is entirely ordinary, culturally established over centuries, and not generally regarded as a welfare issue in the way it would be read elsewhere. Outside Japan the use of live fish as bait or as decoys ranges from unremarkable to prohibited: several European countries restrict or ban livebaiting outright, and where it is permitted it is frequently subject to conditions about the origin of the fish and the water it may be used in — largely for biosecurity reasons rather than welfare ones.
FishingHQ's position on this is the same as its position on every practice where genuine disagreement exists: describe the practice accurately, name the objection accurately, and do not pretend the matter is settled in either direction. What can be said without controversy is that the method is inseparable from the live decoy — there is no version of tomozuri without it — and that a reader outside Japan should establish what is permitted where they are before assuming any of it transfers.
There is also a biosecurity dimension that is not about welfare at all and applies wherever live fish are moved: a decoy carried from one river to another carries whatever it is carrying. Where the practice is legal, sourcing decoys from the water being fished is the answer.
Practitioner consensus
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
- Fishers' Craft and Lettered Art: Tracts on Fishing from the End of the Middle Ages — University of Toronto Press, 1997 (Scientific literature)Relied on for: The long documentary record of traditional and pre-industrial fishing practices, and how such traditions are read.States this directlyCitation checked — the work exists and is described correctly
- Words of the Lagoon: Fishing and Marine Lore in the Palau District of Micronesia — University of California Press, Berkeley, 1981 (Reference work)Relied on for: That traditional fishing practices encode detailed knowledge of quarry behaviour, and that the practice is frequently the record of the biology.Background and mechanism onlyCitation checked — the work exists and is described correctly
- Check Clean Dry — biosecurity guidance for water users — GB Non-native Species Secretariat (Conservation authority)Relied on for: Biosecurity guidance on the movement of live fish and water between catchments, and the disease and invasive-species risk it carries.Background and mechanism onlyPassage read and verified
Where to go next
What it catches
What these connections rest on (1)
Practitioner consensus — 1 connection
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Ayu
The method-species association is convention; the territoriality it exploits is recorded biology, and the two are cited separately rather than blended.
- FishBase: a global information system on fishes — Froese, R. and D. Pauly, eds. — FishBase Consortium (Scientific institute)Relied on for: Diet, habitat association and territorial feeding behaviour recorded for the species concerned.States this directlyPassage read and verified
- General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated angling practice and belief, recorded as practitioner consensus rather than as tested fact.Background and mechanism onlyCitation checked — the work exists and is described correctly
Established angling practice for this species, recorded as convention. The note states the property of the animal or its water that makes the method the answer.
- Fishers' Craft and Lettered Art: Tracts on Fishing from the End of the Middle Ages — University of Toronto Press, 1997 (Scientific literature)Relied on for: That fishing practices develop around the quarry and water available to them, and the historical method of reading such traditions.Background and mechanism onlyCitation checked — the work exists and is described correctly
- FAO fishing gear types and fishing technology information — Food and Agriculture Organization of the United Nations (Scientific institute)Relied on for: Classification and operation of the gear type described.States this directlyCitation checked — the work exists and is described correctly
History and culture
What these connections rest on (1)
Practitioner consensus — 1 connection
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Ayu tomozuri: fishing with a live decoy
Cultural placement of a living tradition, recorded at the level the available sources support and no higher.
- Fishers' Craft and Lettered Art: Tracts on Fishing from the End of the Middle Ages — University of Toronto Press, 1997 (Scientific literature)Relied on for: The relationship between fishing technique, seasonal rights and community practice in pre-industrial fisheries.Background and mechanism onlyCitation checked — the work exists and is described correctly
- General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated description of regional angling traditions, recorded as consensus rather than as scholarship.Background and mechanism onlyCitation checked — the work exists and is described correctly
More method
Not related to this page — just the rest of the section, because this record connects to very little and a short page should still lead somewhere.
Check the rules before you fish
Fishing laws, bylaws, access rules, seasons, bait restrictions and permitted methods vary by location and can change. Check the current rules from the relevant authority and the water you intend to fish before fishing.
Check with:
- Current national or regional law for where you are fishing
- Current local bylaws
- The relevant fisheries authority
- The landowner, club or fishery whose water it is
- Any restrictions specific to the species or the method you intend to use
Sources for this page
- Fishers' Craft and Lettered Art: Tracts on Fishing from the End of the Middle Ages — University of Toronto Press, 1997 (Scientific literature)Relied on for: The long documentary record of traditional and pre-industrial fishing practices, and how such traditions are read.States this directlyCitation checked — the work exists and is described correctly
- Words of the Lagoon: Fishing and Marine Lore in the Palau District of Micronesia — University of California Press, Berkeley, 1981 (Reference work)Relied on for: That traditional fishing practices encode detailed knowledge of quarry behaviour, and that the practice is frequently the record of the biology.Background and mechanism onlyCitation checked — the work exists and is described correctly
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