Freshwater · Spring to autumn; Lake Biwa lure fishing peaks with warming water

Hasu (Three-lips)

Opsariichthys uncirostris

Both sides must be written: the Lake Biwa endemic subspecies of hasu is Red List VU (vulnerable) and protected in its native lake. Where the species has been introduced — Kanto and beyond — it is instead treated as an invasive problem predator. In Lake Biwa it is a lure target; elsewhere it is a bass-fishing bycatch.

Seasons · Peak

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Hasu (Three-lips) — Photo: Ffish.asia, CC BY 4.0 — Wikimedia Commons

Identifying features

Distinctive upturned mouth split into three lobes — the 'three-lips' name
Streamlined, silvery predatory body unlike the deep-bodied funa
Lower jaw protrudes and points upward for surface and mid-water feeding
Relatively large scales and a forked tail for chasing prey
Breeding males show reddish-orange colour on the head and fins

Habits

An active predator of small fish, unusual among the carp family
In Lake Biwa it follows schools of small fish in open water
Where introduced beyond its native range it is treated as an invasive problem predator that eats native small fish
A known lure target in Lake Biwa and a bass-fishing bycatch elsewhere
Spawns in spring to early summer; males develop breeding colour and tubercles

Distribution

Regional coverage expanding

Where to find them

Northern Lake Biwa, Shiga — open water and rocky shores (endemic subspecies protected here; follow local rules)
Lake Kasumigaura, Ibaraki — introduced population, lure bycatch
Tone River system, Kanto — introduced fish in river runs

Where they live

Lake Biwa — its native home, in open and rocky waterLarge rivers and lakes where it has been introduced, such as Lake Kasumigaura and the Tone systemRiver runs and lake shores where small fish gather

How to catch them

Lure fishing in Lake Biwa Lake

Rig: Light spinning tackle casting small spoons or minnows along rocky shores and open water of Lake Biwa

Bait/lure: Small spoons, spinners and minnow plugs

Key tip: Watch for small-fish surface activity; hasu slash into baitfish schools on the hunt.

River lure fishing for introduced fish River

Rig: Spinning rod working small minnow plugs and spoons through runs of the Tone system and similar introduced waters

Bait/lure: Small minnows and spoons in river runs

Key tip: Fish edges and current seams where predators wait for small fish.

Best baits & lures

Small spoons and spinnersMinnow plugsLive small fish or worm baits in traditional fishing

Techniques for Hasu (Three-lips) →

Baseline setup

Rod: Light to medium-light spinning rod 6-7 ft
Line: 6-10 lb PE or nylon for lure fishing
Terminal: Small spoons, spinners and minnow plugs; small hooks for bait fishing

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 8-12 in (20-30 cm); large Lake Biwa fish to about 16 in (40 cm)

On the table

Eaten locally around Lake Biwa in traditional preparations, but introduced fish elsewhere are mainly a lure-fishing bycatch/target and are not prized; in its native lake the endemic subspecies is protected and must not be kept.

Similar species

Pale ChubPale chub (oikawa) is smaller and slimmer with a normal, non-three-lobed mouth; hasu is larger, predatory, and identified by its upturned three-lobed mouth

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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