Saltwater · Year-round in warm southern waters; best in summer when schools crowd the piers

Mottled Spinefoot

Siganus fuscescens

The mottled spinefoot — 泥猛 — is the ever-present pier and reef fish of southern China: a schooling algae-grazer taken on tiny hooks and dough baits, famous for its venomous spines. In Japan the aigo is a standard reef and pier catch in Kyushu and Okinawa, where its venomous fin spines demand careful handling.

Seasons · Peak

Jan

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Mottled Spinefoot — Photo: User:Izuzuki, CC BY 4.0 — Wikimedia Commons

Identifying features

Compressed, oval body mottled olive-brown over a silvery belly
Small mouth with a single row of close-set teeth for grazing algae
Thirteen venomous spines in the dorsal fin, plus venomous pelvic and anal spines
Fins and body pattern darken and blotch when the fish is stressed
Small, rough scales giving the skin a slightly leathery feel

Habits

Indo-Pacific species, common year-round off southern China at piers and reefs
Feeds in schools, grazing algae and seagrass from rocks and harbour walls
Juveniles gather in large schools over flats; adults in smaller groups
Most active by day, retreating into reef cover at night
The dorsal, pelvic and anal spines are venomous — a sting is painful, so unhook with great care

Distribution

Regional coverage expanding

Where to find them

Pier legs and harbour walls with algae growth
Reef flats and rocky points on a rising tide
Breakwater rocks around southern ports

Where they live

Piers and harbour walls in southern ChinaShallow reefs and reef flatsSeagrass and algae-covered rocks

How to catch them

Small-hook dough float fishing at piers Shore

Rig: Light float rig, tiny size 12-16 hooks, pea-sized dough or algae bait fished beside pier legs

Bait/lure: Dough, algae

Key tip: Chum lightly with crumbled dough; spinefoot bite in quick pecks, so strike fast and lift clear of the school.

Light float rigs over reef flats Shore

Rig: Long light rod, small float set to fish just above the reef, algae or shrimp bait

Bait/lure: Algae, shrimp pieces

Key tip: Fish a rising tide in the morning; keep the bait moving slowly over the flat so the school follows it up.

Best baits & lures

Dough and bread baitsAlgae and seaweedSmall pieces of shrimp

Techniques for Mottled Spinefoot →

Baseline setup

Rod: Light 9-12 ft float rod
Line: 4-8 lb mono
Terminal: Tiny hooks, small floats, split shot

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 6-10 in; large fish to about 12 in

On the table

Good — a popular pan fish in southern China; handle with extreme care when unhooking because the dorsal spines are venomous, and use a towel or tool, never bare fingers.

Similar species

NibblerNibbler is a deeper-bodied, plain dark-grey reef fish without venomous dorsal spines; mottled spinefoot is mottled olive, more oval, and its 13 dorsal spines are venomous

Spotted ScatSpotted scat is a round, strongly spotted disc with a steep forehead found in estuaries; mottled spinefoot is an oval algae-grazer of reefs and piers with mottling rather than round spots

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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