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Saltwater ยท Year-round at piers and rocks; winter-spring best

Japanese Surfperch

Ditrema temminckii

A year-round standard of Japanese piers, caught on rock and float rigs. Despite its name โ€” 'umi-tanago' means sea bitterling โ€” it is not a bitterling at all but a surfperch, and like all surfperches it is live-bearing. Do not lump it with the pure-freshwater yaritanago in this guide: the resemblance is name only.

Seasons ยท Peak

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Japanese Surfperch
Photo: ใ‚ฟใ‚ฆใƒŠใ‚ฎ, CC0 โ€” Wikimedia Commons

Identifying features

  • Deep, oval, compressed silvery body โ€” a surfperch shape, not a carp shape
  • Small mouth and a long-based dorsal fin along the back
  • Colour silvery olive to golden-brown, sometimes with faint darker mottling
  • Tail moderately forked; fins often carry a yellowish tint
  • Name trap: 'umi-tanago' means 'sea bitterling', but it is NOT a bitterling โ€” it belongs to the surfperch family (Embiotocidae)

Habits

  • Live-bearing: females give birth to fully formed young, mainly in spring โ€” a surfperch family trait
  • Feeds on small crustaceans, worms and other tiny invertebrates picked from rocks and weed
  • Holds close to structure and kelp rather than open sand
  • Most active in the cooler months around piers, though present all year
  • Moves in small loose groups rather than tight schools

Distribution

Regional coverage expanding

Where to find them

  • Tokyo Bay piers with rock and kelp
  • Miura Peninsula rocky coast, Sagami Bay
  • Seto Inland Sea harbours and rocky margins

Where they live

Rocky piers and breakwaters with kelp nearbySeagrass beds and sandy-rock edges in shallow baysRocky shore (iso) margins and harbour walls

How to catch them

Float fishing from piers Shore

Rig: Light float rig with a small hook (size 6-10) fished beside rocks, kelp or harbour walls from a pier

Bait/lure: A small shrimp or worm piece

Key tip: Fish just off the bottom near structure and keep baits small โ€” big baits are ignored.

Light rocky-shore (iso) fishing Rock fishing

Rig: Light bottom or float rig cast along rocky shore edges and seagrass beds

Bait/lure: Clam or shrimp pieces on light tackle

Key tip: Work the rig slowly along the rock wall; surfperch pick baits right against the wall, not in open water.

Best baits & lures

Small shrimp piecesMarine worm piecesClam pieces

Techniques for Japanese Surfperch โ†’

Baseline setup

  • Rod: Light 7-9 ft pier or rock rod
  • Line: 4-8 lb mono
  • Terminal: Small floats or light bottom rigs, hooks size 6-10

Recommended gear for this species

Rod ยท Best value

9' 5-weight fly rod outfit

โ‰ˆ US$180-260

Covers chironomid lakes and small rivers with one setup.

Flies ยท Budget

Chironomid assortment (30 patterns)

โ‰ˆ US$25-40

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

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

Typical size

Common 6-8 in (15-20 cm); large fish to about 11 in (28 cm)

On the table

Good โ€” a mild white-fleshed fish eaten grilled, simmered or as sashimi in Japan; best from clean water.

Similar species

Walleye SurfperchWalleye SurfperchThe walleye surfperch is a North American Pacific species with black-tipped pelvic fins and very large eyes; Japan's umi-tanago is warmer gold-tinted and a rock and pier fish of Japanese coasts

Regulations vary by area and can change in-season โ€” always check the official rules for your area before you fish. Regulations guide โ†’

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