Kawahagi (Filefish) Fishing From Piers: Rigs, Bait and Reading Bites in the "Kimo-Pan" Season
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Minagiman's Fishing Adventures in Japan
Aji (Japanese Horse Mackerel): Maaji, Maruaji and Muroaji — and the “Zengo” Scutes
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The fish most Japanese anglers mean by “aji” is maaji, the Japanese horse mackerel (Trachurus japonicus). Found along coasts all over Japan, it can be caught from piers, beaches and boats. It is strongly migratory, moving in large schools and feeding on small fish and plankton.
Maaji, maruaji and muroaji
These three are often confused:
- Maaji (Japanese horse mackerel): deeper-bodied, often yellowish (“kiaji”). The most common and considered the tastiest.
- Maruaji (Japanese scad): as the name (“round aji”) suggests, a rounder body with a bluish back; more active and more often near the surface.
- Muroaji (mackerel scad): even slimmer and longer, and said to lose freshness faster.
A key feature is the zengo (scutes) — hard, spiky scales along the side. In maaji and maruaji they run clearly along the lateral line; in muroaji they are less obvious.
Why they are where they are
Aji come inshore following plankton and small fish attracted to lights at night — which is why pier and beach lights are the classic ajing spots. They also hold on current lines, along pier walls and anywhere with good water movement where bait gathers.
Season
Aji can be caught all year, but spring to early summer, when water temperature stabilises, and autumn, when bait increases, are the best times for numbers. Autumn is a prime ajing season on the Enshu-nada coast too.
When hooked
Aji have soft, easily torn mouths. Hard hooksets or forcing the fight lead to lost fish. Keep reeling at a steady speed and avoid sudden changes in tension.
Handling
The zengo scutes are sharp and can stick into your fingers. Hold the fish firmly from the head end or use a fish grip.
Tackle (surf and pier ajing)
- Rod: about 6–7 ft dedicated ajing rod (L)
- Reel: small 1000–2000 spinning reel
- Line: ester or PE 0.2–0.4 with 0.8–1.5 fluorocarbon leader
- Jigheads: about 0.5–2 g depending on conditions
Eating and keeping
Aji spoil quickly. Ice them as soon as possible and keep them cold. They are superb as sashimi, namero (chopped with miso), aji fry or nanban-zuke (marinated fried fish). As with other oily fish, watch for anisakis parasites — check carefully, or cook or freeze before eating.
Read next
- Winter ajing beginner’s guide
- Advanced winter jighead ajing
- Ajing float and Carolina rigs
- Ribbonfish (tachiuo) guide
- Anisakis and Your Catch: Eating Sashimi More Safely
ABOUT ME
Born in 1994. Originally from Hyogo Prefecture, I moved to Iwata City in Shizuoka Prefecture in search of the sea. I am an Enshunada surf angler who enjoys surf fishing. I am also active on YouTube, and my fishing grounds range from Irago to Iwata.
