Sargassum fish

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The sargassum fish is a frogfish about 15 cm long, blotched yellow and brown, that crawls through floating sargassum weed on hand-like fins. Its colour and shape match the weed so well that prey swim right up to it.

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At a glance

Class: Fish
Lives in: Drifting sargassum in the Sargasso Sea and other warm oceans
Diet: Meat eater (carnivore)
Length: about 0.15 m
Conservation status: Least Concern (IUCN LC)
Habitat: open ocean

Quick answers

Where does the Sargassum fish live?

It lives in the open ocean of the Atlantic, Pacific and Indian oceans. On the globe you can find it near Drifting sargassum in the Sargasso Sea and other warm oceans.

How big is the Sargassum fish?

It grows to about 0.15 m.

What does the Sargassum fish eat?

Its diet: meat eater (carnivore).

Is the Sargassum fish endangered?

It is listed as Least Concern (IUCN LC).

The sargassum fish is a small frogfish that lives among drifting sargassum seaweed in warm seas. It is mottled yellow, green and brown, and its skin is covered in little weed-like flaps, so it blends in almost perfectly with the golden floating weed. It can also change colour quickly from light to dark and back.

It grows up to about 20 centimetres, though many are around 15. It lives in tropical and subtropical waters in the Atlantic, Indian and Pacific oceans, usually near the surface. Its scientific name, Histrio, means actor, probably for its clever way of hunting.

A fish that walks on seaweed

The sargassum fish does not swim much. Its pectoral fins are stalked and able to grip, so it clambers through and clings to the weed stalks like a climber. The front spine on its head has become a thin fishing rod, called the illicium, with a fleshy lure at the tip. Prey that swims close is gulped down in a flash, when the fish darts forward and forcefully expels water through its gill openings.

Life in a floating forest

Sargassum weed drifts in great mats, and the Sargasso Sea gave this fish its first scientific description, by Carl Linnaeus in 1758. Its gills open as small pores near the base of the pectoral fins, and its mouth is very wide. To breed, a female rises quickly to the surface and lays a mass of eggs held together by sticky mucus.