Freshwater · Spring to autumn in western Japan streams

Dark Chub

Candidia temminckii

The dark chub (kawamutsu) is a small stream fish of western Japan, part of the informal 'Japanese stream small fish trio' with pale chub (oikawa) and ugui. A dark lateral band marks it, and males colour up strongly in the breeding season. It is a common fly and micro-bait bycatch in char and yamame streams.

Seasons · Peak

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Dark Chub — Photo: Ffish.asia, CC BY 4.0 — Wikimedia Commons

Identifying features

A dark, dusky lateral band along the side — the key mark vs pale chub
Slender chub body with a slightly down-turned mouth for bottom grazing
Breeding males darken and show stronger colour along the band
Scales small; fins plain, with breeding colour on males
Lacks the bright silver flash and upturned feeding style of pale chub

Habits

Part of the informal 'Japanese stream small fish trio' with pale chub (oikawa) and ugui
Schools in runs and pool tails feeding on insects and algae
Males colour up strongly in the breeding season with a darkened, vivid band
A common fly and micro-bait bycatch in char and yamame streams
Spawns in spring to early summer over gravel

Distribution

Regional coverage expanding

Where to find them

Yodo River system, Kansai — clear tributary streams
Mountain streams of Hiroshima and Okayama, western Honshu
Tributaries of the Chikugo River, Kyushu

Where they live

Clear streams and small rivers of western JapanGravel runs and pool tails in forested valleysSlow edges and backwaters of lowland streams in its range

How to catch them

Micro-bait stream fishing River

Rig: Light keiryu rod with a tiny hook and split shot or a fine float, drifted through pool tails and gravel runs

Bait/lure: Tiny worm pieces or nymphs

Key tip: Fish very fine — kawamutsu are wary and heavy rigs scatter the school.

Fly fishing as a char/yamame bycatch River

Rig: Light fly rod with small dry flies or nymphs presented in the same runs fished for char and yamame

Bait/lure: Small dry flies and nymphs

Key tip: Present small flies when small fish are feeding actively; dark chub rise readily to insects.

Best baits & lures

Small earthworm piecesStonefly and mayfly nymphsTiny dough baits and micro flies

Techniques for Dark Chub →

Baseline setup

Rod: Light keiryu rod or small spinning/fly rod
Line: 2-4 lb fine nylon
Terminal: Tiny hooks (size 14-18), fine float or split shot, micro flies

Recommended gear for this species

Rod · Best value

9' 5-weight fly rod outfit

≈ US$180-260

Covers chironomid lakes and small rivers with one setup.

Flies · Budget

Chironomid assortment (30 patterns)

≈ US$25-40

Chironomids are 60% of a lake rainbow's diet in spring.

Picks come from our rule library — never paid placements. Prices are guides; affiliate links may earn us a commission.

Typical size

Common 4-6 in (10-15 cm); large fish to about 8 in (20 cm)

On the table

Not usually eaten — a small stream fish taken for fun, as bycatch, or in traditional small-fish dishes in some areas; most anglers release it.

Similar species

Pale ChubPale chub (oikawa) is brighter silver with no dark lateral band and feeds at the surface; dark chub carries a dusky band and grazes deeper

Regulations vary by area and can change in-season — always check the official rules for your area before you fish. Regulations guide →

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