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Sargassum Anglerfish

Sargassum Anglerfish

Histrio Histrio

Quick Facts

Scientific nameHistrio Histrio

Other namesMarbled Angler, Mouse Fish, Sargassum Frogfish, Sargassum Fish

FamilyAnglerfish / Antennaridae

Distribution

Habitat & AU DistributionMangrove seagrasses & floating sargassum algae in pelagic waters

The Sargassum Anglerfish is a small, lumpy, weed-draped fish that grows to about 20 cm long. It is one of the most elaborately camouflaged fish in the ocean.
Its whole body is covered in fleshy flaps, filaments and skin tags that look just like the fronds and branches of floating seaweed. Sitting still inside a mat of Sargassum algae, it is almost impossible to spot.
Its colour can range from pale cream through to greenish or dark brown, with an irregular pattern of blotches and spots. This variation lets each fish match the particular patch of weed it calls home.
Unlike most of its close relatives, the Sargassum Anglerfish has smooth skin rather than prickly, warty skin. That smooth surface is part of what makes it look so much like drifting algae.
In Australia, this fish is found from Rockingham in Western Australia, across the tropical north, and down the east coast as far south as Batemans Bay in New South Wales. Juveniles sometimes wash close inshore, occasionally turning up near Sydney beaches on floating weed mats.
Beyond Australia, it ranges through all tropical and subtropical seas except most of the eastern Pacific Ocean. That makes it one of the more widely distributed anglerfish species in the world.
The Sargassum Anglerfish spends most of its life drifting with floating mats of Sargassum algae out in the open ocean. Several individuals, including juveniles, may share the same algal mat at once.
Rather than swimming through open water, it clambers over the weed using its thick, arm-like pectoral fins. This gives it an almost hand-over-hand way of moving through its floating home.
Like other anglerfish, it carries a built-in fishing rod on its head. A modified spine acts as a rod, tipped with a lure it can wiggle to attract small fish and other prey close enough to ambush.
When a meal comes close enough, the Sargassum Anglerfish strikes with one of the fastest attacks of any fish. The strike happens in milliseconds, far too quick for the prey to react.
When threatened by a predator, this fish has an unusual escape move: it can jump clear out of the water and land on top of the algal mat. It can stay out of the water for some time before slipping back in.
Sargassum Anglerfish have also been found in coastal environments such as mangroves and among seagrasses, though drifting open-ocean weed mats are their most common home.

Species Interaction

Sargassum Anglerfish: A Drifting Oddity for the Curious Few

Snorkelling & Diving
Research & Rare Encounters
Ecosystem Role

Underwater photographers and divers occasionally find one clinging to a floating weed raft, perfectly camouflaged among the fronds. Juveniles sometimes wash close to Sydney beaches with their drifting Sargassum, bringing the species to the attention of beachgoers and naturalists. Scientists study it as part of the broader ecology of open-ocean drift communities.

Species
Sustainability

Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Teleostei
Order: Lophiiformes
Family: Antennariidae
Genus: Histrio
Species: Histrio histrio

Conservation Status

The IUCN assessed Histrio histrio as Least Concern globally in its most recent evaluation, noting the species is generally common across its wide range. Localised population declines have been recorded in the southwestern Indian Ocean, linked to habitat loss and pollution affecting floating Sargassum. No EPBC listing applies in Australia.