Blue Weed Whiting

Haletta Semifasciata
Blue Weed Whiting - Marinewise © 2025 MarineWise

Quick Facts

Scientific name Haletta Semifasciata
Other names Blue Rock Whiting, Grass Whiting, Rock Whiting, Stranger Whiting, Weed Whiting, Semibanded Weed Whiting
Size Up to 29 cm (11 in)
Weight Under 1.25 kg (2.75 lb)

Distribution

Habitat & AU Distribution Coastal waters, estuaries, bay & harbours amongst sandy & seagrass areas
Depth Range 1 - 20 m (65 ft)
Blue Weed Whiting Distribution

Interesting Info

  • The Blue Weed Whiting is a small wrasse-like fish that lives only in southern Australian waters, from Jurien Bay in Western Australia, across the Great Australian Bight, to western Victoria and northern Tasmania.
  • It is the only species in its genus Haletta, making it a unique member of the wrasse family (Labridae).
  • The body is slender with bluish to greenish tones, often with faint vertical bars, giving it the “blue” and “semi-banded” look described in its scientific name.
  • It lives in shallow coastal waters, usually 0–20 m (0–65 ft) deep, over seagrass beds, algal reefs, and sandy bottoms with weed cover.
  • Juveniles often inhabit very shallow seagrass beds, where their mottled colours make them almost invisible to predators.
  • Adults are herbivores, feeding mainly on filamentous algae scraped from seagrass and rocks, though they may also ingest small invertebrates while grazing.
  • Blue Weed Whiting often swim in small groups close to the bottom, where their colours blend with weed and seagrass.
  • Their diet makes them ecologically important grazers, helping to keep algal growth in check on shallow reefs.
  • Males and females look very similar, though males may show slightly brighter blue tones during breeding.
  • They are thought to spawn in summer, releasing eggs into the water column, which drift until hatching.
  • The lifespan is not well studied but is likely around 5–7 years, similar to other small wrasses of temperate reefs.
  • Predators include larger reef fish, squid, and seabirds that hunt over seagrass beds and shallow reefs.
  • Although sometimes mistaken for juvenile wrasses, the Blue Weed Whiting is a distinct species with its own genus and ecological niche.
Species Interaction

Recreational Fishing, Snorkeling & Diving

Blue Weed Whiting are not a primary target for recreational fishing, they are occasionally caught as a by-catch when fishing for other species. For snorkelers and divers, observing them can be a rewarding experience. Their vibrant blue coloration and distinct banding patterns make them visually striking, especially against the backdrop of seagrass beds and rocky reefs.

Scientific Classification

Kingdom: Animalia

Phylum: Chordata

Class: Actinopterygii

Order: Perciformes

Family: Odacidae

Genus: Haletta

Species: Haletta Semifasciata

Conservation Status

The Blue Weed Whiting is considered a species of least concern in Australia. Their population is stable, and there are currently no major conservation concerns regarding their numbers.

How to catch
Blue Weed Whiting

Catch Difficulty: Easy

Tackle: Running Sinker Rig

Bait: Crab, Fresh cut flesh baits, Prawns, Shellfish, Squid, Worms, Yabbies

Technique: Keep bait on the bottom

Popularity: Not targeted

Recreational Viewing
- Snorkeling & Scuba

Finding: Intermediate

Temperament: Shy

Location: Inner Reef, Lagoon, Seagrass Beds

Danger: None