Butterfish
Butterfish (greenbone) is a New Zealand endemic found in shallow kelp beds from North Cape to the Snares Islands, most abundant south of Cook Strait. Spearfishers rate it among the best eating fish in the country.
Line fishing for butterfish is genuinely difficult — they're notoriously line-shy — but a small number of dedicated anglers do target them with light tackle and shellfish or weed baits.
Scientific Name: Odax pullus
Also known as Greenbone, mararī, rarī, kōeaea, marare, matohe, tarao
- Protogynous hermaphrodites: juveniles are golden-bronze with broken white dashes along the flanks; adult females are brown to olive-green with a pale lateral band.
- Males turn grey-brown to blue-grey with conspicuous blue patterning on the head, flanks, and fins — the most visually striking phase of the species.
- Named for their distinctly blue-green bones — unmistakable once you've filleted one.
- Typically 30–50 cm and 1–1.5 kg; fish over 40 cm are more common in colder southern waters, with a recorded maximum around 70 cm.
What to know
Habitat Distribution
- Endemic to New Zealand — found nowhere else — from North Cape south to the Snares Islands, with the largest concentrations south of Cook Strait.
- Kelp and brown algae beds over rocky reef are the core habitat; most fish sit in 5–20 m of water, rarely deeper than 40 m.
- The main commercial and recreational fishery runs through Cook Strait — Tasman Bay, Castlepoint, and Kaikoura — with a secondary population around Stewart Island.
- Bigger fish trend south: the colder waters of Southland and Stewart Island produce the largest specimens.
Key Locations
- Cook Strait corridor — Tasman Bay, Castlepoint, and Kaikoura — the centre of both commercial and recreational effort.
- Stewart Island and Southland coast — a distinct southern population with larger average fish size.
- Wellington's South Coast (Red Rocks area) — accessible kelp reef popular with spearfishers.
- Chatham Islands (Waitangi Wharf area) — noted for unusually fishable butterfish on line gear.
Specific Spots
- Dense kelp canopy over broken reef is the key — butterfish graze directly on the algae and rarely stray far from it.
- Shallow rocky edges in 5–10 m hold the most fish; look for Carpophyllum or Lessonia kelp growth rather than bare rock.
- For line anglers, weedy pockets and kelp margins where an unweighted bait can drift naturally are the most productive positions.
- Wharves and jetties over weedy ground — such as Waitangi Wharf on the Chatham Islands — can concentrate fish in accessible, fishable water.
Butterfish FAQ
Answers from onWater's species guide.
What are the best lures and bait for Butterfish?
Shellfish baits, crayfish flesh is the standout, on a small hook with no weight, allowed to drift naturally into kelp edges. Weed is also used. Presentation matters more than bait choice: the bait needs to move freely and naturally in the current, not sit hard on the bottom under a sinker.
When is the best time to fish for Butterfish?
Accessible year-round in suitable kelp habitat, but spawning fish (September–January depending on region) may be more concentrated and visible in shallower reef areas. Summer and autumn (January–April) offer the best diving visibility in most areas, which is the primary factor for spearfishers.
How do you catch Butterfish?
Spearfishing is by far the most effective and widely practised method, patient stalking through kelp in 5–10 m of water. Line anglers who do target them work unweighted shellfish or weed baits on light gear from shore or shallow-water boats, focusing on kelp edges and weedy pockets where fish are actively grazing.
What do Butterfish eat?
Butterfish are strict herbivores, they graze on large brown seaweeds including Carpophyllum, Lessonia, and giant kelp (Macrocystis). This makes them unusual among reef fish and explains why conventional lures don't work on them.
Where do Butterfish live?
Endemic to New Zealand, found nowhere else, from North Cape south to the Snares Islands, with the largest concentrations south of Cook Strait. Kelp and brown algae beds over rocky reef are the core habitat; most fish sit in 5–20 m of water, rarely deeper than 40 m.
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