Freshwater · May-September; night activity in warm months

Slender Catfish

Silurus microdorsalis

Korea's small endemic Silurus — the slender 미유기, sister species to the Amur catfish. Nocturnal in middle and lower river reaches; fished the same way as the Amur catfish on slightly finer tackle. Despite earlier list assumptions it is not on Korea's official endangered list — but care with identification is still due, as with all native catfishes.

Seasons · Peak

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Slender Catfish — Photo: Kim, Hyun-tae, CC BY 4.0 — Wikimedia Commons

Identifying features

Slender scaleless body with only 2 pairs of barbels (the Silurus mark)
Tiny dorsal fin — 'microdorsalis' means small-backed
Grey-olive without the Amur catfish's dark marbling
Flattened head with a broad mouth
Long anal fin running toward the tail

Habits

Nocturnal and bottom-oriented
Endemic to Korea — the Amur catfish's small sister species
Hides in cover by day
Hunts small fish and shrimp at night
Torpid in winter

Distribution

Regional coverage expanding

Where to find them

Han River reaches at Chungju
Geum River pools at Gongju
Middle Nakdong at Andong

Where they live

Middle-to-lower reaches of the Han, Geum and Nakdong with moderate flowDeeper pools with mud-sand bottomsSlow side channels and reservoir inflows

How to catch them

Night fishing in river pools River

Rig: Bottom rig with worm or fish piece set in deep pools of river bends at night

Bait/lure: Large earthworm or fish piece

Key tip: Fish after dark; small Silurus are warier than Amur catfish — a slack line on the bite helps.

Live-bait work on slow edges River

Rig: Live baitfish under a float or on the bottom along slow edges and backwaters at mid-summer

Bait/lure: Live small fish

Key tip: Where baitfish gather, 미유기 patrol at dusk; a quiet approach is everything.

Best baits & lures

EarthwormFish piecesLive baitfish

Techniques for Slender Catfish →

Baseline setup

Rod: Medium 8 ft river rod
Line: 8-12 lb monofilament
Terminal: Hooks size 4-6, medium sinkers

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 10-14 in (25-35 cm); large fish about 18 in (45 cm)

On the table

Edible — a modest relative of the Amur catfish; rarely targeted for the table.

Similar species

Amur CatfishAmur catfish is bigger, longer-barbelled and darkly marbled; slender catfish is the small endemic with a tiny dorsal fin

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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