Arabian Catshark

• Maximum lengthAbout 30 cm (12 in), the only specimen; adults may be larger
• WeightNot recorded; a 30 cm catshark weighs well under 200 g (7 oz)
• LifespanUnknown; no second specimen has ever been examined
• Depth rangeAbout 1,134–1,262 m (3,720–4,140 ft), a single record
• DietUnknown; presumably small crustaceans, squid and fishes
• IUCN statusData Deficient (assessed 2017)

How to recognise an Arabian catshark

Nobody alive has seen an Arabian catshark, so any identification key is built from a description written more than a century ago. The Investigator specimen was a typical small member of its genus: a soft-bodied catshark with a broad, somewhat flattened head, a rounded snout, small eyes set high on the head, and a long, low tail without a crest of enlarged denticles along its upper edge. There are two small dorsal fins, the second slightly larger than the first, an anal fin smaller than either, and no fin spines.

Colour was the most striking thing recorded: a blackish body with a frosted or hoary grey surface, as if dusted with ash, and whitish tips to some of the fins. Garman separated it from the bristly catshark (Bythaelurus hispidus) of the Indian and Andaman slopes by its longer snout, smaller eyes and smaller anal fin. The name alcockii honours Alfred Alcock, the surgeon-naturalist of the Investigator whose account of the fish Garman worked from.

A deepwater catshark hauled up from the Arabian Sea slope today would need careful comparison with the whole genus, which has grown from a handful of species to more than a dozen since 2016 as trawl and seamount surveys in the western Indian Ocean turned up new ones. Until a second specimen is caught and kept, the safest statement is that a small, dark, soft-skinned catshark from below 1,000 m between Oman and Pakistan could be this species, and should be preserved rather than discarded.

How big does the Arabian catshark get?

The only measurement that exists is the one Alcock made on deck: about 30 cm (12 in) in total length. Older websites, including the previous version of this page, quote that as the maximum size of the species, but it is the length of one fish, and there is no way to tell whether it was a full-grown adult, a half-grown juvenile or a newborn. Nothing in the description settles the question, and the lost specimen cannot be re-examined.

The relatives give a range to work with. Deepwater catsharks of the genus Bythaelurus are all small: the largest, the jaguar catshark of the Galápagos, reaches about 50 cm, most species mature between 30 and 45 cm, and the smallest are adult below 30 cm. A 30 cm Arabian catshark could therefore be an adult, and it is unlikely that the species ever exceeds half a metre.

Weight has never been recorded. A slender catshark of 30 cm weighs somewhere under 200 g; even a 50 cm adult of a related species is well under a kilogram. On our list of the smallest sharks this would be a contender, but the honest answer is that we know one number, and one number is not a size range. The bar below shows that single length against a 1.8 m diver.

Where the Arabian catshark lives

One locality: the continental slope of the north-western Arabian Sea, between the coasts of Oman, Iran and Pakistan and the open basin to the south, at a depth generally cited as 1,134–1,262 m (3,720–4,140 ft). That figure comes from the sounding taken when the Investigator lowered her trawl in the 1890s, and it is the whole of what is known about the species' habitat.

It is a revealing depth. The Arabian Sea has one of the most intense oxygen minimum zones in the world ocean: between roughly 200 and 1,000 m the water holds almost no dissolved oxygen, and few fish can live there. Below about 1,000 m oxygen recovers, the temperature settles at a stable 5–8 °C, and the muddy slope supports crustaceans, squid and small fishes that a catshark could feed on. The Arabian catshark was found just beneath the dead zone, in the first band of habitable deep water, which may be exactly where a small, slow, bottom-hugging shark would be expected to live.

Whether it also occurs off India, in the Gulf of Oman or along the Somali slope is unknown; modern deepwater surveys in the region have not reported it. A species confined to a slice of slope just below the oxygen minimum would have a narrow, fragmented range, but the truth is that nobody has looked hard enough in the right place to say.

What the Arabian catshark probably eats

No stomach has ever been examined, so what follows is inference. Every deepwater catshark whose diet is known feeds on the small animals of the deep mud and the water just above it: shrimps and other crustaceans, small squid, lanternfish and other little mid-water fishes that sink or stray to the bottom, and polychaete worms. The jaws of Bythaelurus species carry many rows of tiny, multi-cusped teeth suited to gripping soft-bodied prey, not to cutting, and their mouths are small. The Arabian catshark, at 30 cm and with the same build, would eat at the same table.

Hunting at 1,200 m is not hunting in any visual sense. Sunlight ends hundreds of metres above, and the only light is the bioluminescence of other animals. A catshark at that depth finds food by smell, tracking scent plumes along the current, and at the last moment by the electrical sense of the ampullae of Lorenzini, which detect the muscle activity of a buried shrimp or a resting fish.

Deep-slope sharks eat little and slowly. In a cold, food-poor environment a fish this size may go weeks between meals, and the large, oil-rich liver typical of deepwater catsharks doubles as an energy store and a buoyancy aid, letting the animal hover over the mud without wasting effort. If the Arabian catshark follows its relatives, it is an unhurried scavenger and opportunist rather than a pursuer of anything.

Behaviour and senses

What can be said about the behaviour of an animal seen once, dead, on the deck of a Victorian survey ship? Only what its body and its relatives allow. Deepwater catsharks are sluggish, bottom-oriented fish. Submersible footage of species in the same family shows them resting on the sediment or swimming slowly just above it with lazy sweeps of the long tail, occasionally turning to investigate a scent. There is no evidence of schooling, territoriality or migration in any of them, though some gather where food is concentrated.

The sensory picture is one of a smell-and-touch animal. The nostrils are large relative to the head, the lateral line runs the length of the body to register water movement, and the snout carries a dense field of electroreceptive pores. The small eyes, the dark skin and the soft, weakly muscled body are adaptations to a lightless, cold, high-pressure world where being inconspicuous matters more than being fast, features shared across the group and explained on our page on shark anatomy.

It is worth being clear about how thin the evidence is. The previous version of this page credited the species with a keen sense of sight, sharp teeth and a streamlined body; none of those claims rests on the specimen, and the first is almost certainly wrong for a shark from 1,200 m. The most accurate description of Arabian catshark behaviour is that it has never been observed.

Reproduction and lifespan

The reproductive mode of the Arabian catshark is unknown, and the genus does not settle it. Most species of Bythaelurus are oviparous, laying small, tough egg capsules on the sea floor, but at least one, the mud catshark of the Mozambique Channel, retains the eggs and bears a pair of live young. Because no female Arabian catshark has ever been examined, the species could follow either route. The old claim that it "follows an oviparous mode of reproduction" is a guess presented as a fact.

If it lays eggs, the pattern in relatives suggests one or two capsules at a time, deposited repeatedly through the year, each hatching after many months in cold water into a pup a third or a quarter the length of its mother. If it bears live young, litters would be tiny, probably two. Either way, output is low: a few offspring a year at best, the norm for small deep-sea sharks.

Lifespan, growth rate and age at maturity have never been estimated. Deepwater catsharks aged elsewhere grow slowly and live for one to two decades, and cold water and scarce food push those numbers up rather than down (see how long sharks live). For the Arabian catshark all three values remain blank until fresh specimens reach a laboratory.

Is the Arabian catshark dangerous to people?

No, and it could not be. The Arabian catshark lives more than a kilometre below the surface, far beyond the reach of any swimmer, diver or fisherman with a rod, and the only human who has ever handled one was a naturalist sorting a trawl in the 1890s. It is 30 cm long, soft-bodied and equipped with teeth built for shrimps. The SharkSider database holds no incident attributed to this species, and no attack file anywhere mentions it.

The people of the Arabian Sea coast have other sharks to think about, and the bather-relevant species for the region are covered on the pages for Oman and India. As for catsharks in general, the only recorded "incident" involving any member of the group in the world's attack records is a Norwegian diver who prodded a small-spotted catshark he thought was dead and was nipped on his sleeve. The Arabian catshark belongs on any honest list of the least dangerous sharks, and for the least dramatic of reasons: it never comes within a thousand metres of us.

The SharkSider database has no incident attributed to this species. The database draws on the International Shark Attack File, the Global Shark Attack File and verified local reports, and is updated weekly.

Conservation status

The IUCN Red List classes the Arabian catshark as Data Deficient, and it is hard to imagine a species that better deserves the label. With one specimen, one locality, one depth record and no information on population, range, biology or catch, there is nothing to assess against the Red List criteria. It has no CITES or CMS listing and no national protection anywhere; no fishery targets or records it.

That does not mean it is safe. Deepwater trawling and longlining have expanded along the slopes of the Arabian Sea in recent decades, in Oman, Pakistan and India, and any catshark living at 1,100–1,300 m is within reach of gear set for deep shrimps and fish. Small deep-sea sharks taken as bycatch are almost never identified to species, so the Arabian catshark could be dying in nets today without anyone knowing. Its narrow depth band, just beneath the oxygen minimum zone, also exposes it to any expansion of that zone, one of the predicted effects of a warming, stratifying ocean.

The immediate conservation need is knowledge. A single fresh specimen, properly preserved with tissue for DNA, would confirm that the species still exists, fix its identity within a fast-growing genus and allow a real assessment. Deepwater surveys of the north-western Arabian Sea slope, and a habit among observers of keeping rather than discarding small dark catsharks, are the practical steps. The broader picture is on our page on why sharks are endangered.

Similar species and close relatives

The Arabian catshark belongs to Bythaelurus, a genus of small, soft-bodied deepwater catsharks that now numbers more than a dozen species, most of them described from the western Indian Ocean since 2016 as seamount and slope surveys brought up material nobody had seen before. Its closest geographic neighbour is the bristly catshark (Bythaelurus hispidus) of the Indian and Andaman slopes, the species Garman used for comparison; on SharkSider the genus is represented by the jaguar catshark of the Galápagos, larger, spotted and, unusually for the group, filmed alive from a submersible.

Beyond the genus, the family Pentanchidae supplies the look-alikes: the quagga catshark, another poorly known species from the same corner of the Indian Ocean but from shallower water and barred like its namesake; the salamander shark and filetail catshark of the genus Parmaturus, which have the crest of enlarged denticles on the tail that Bythaelurus lacks; and the ghost catsharks of the genus Apristurus, such as the ghost catshark and longnose catshark, which are longer-snouted and often paler. Any small dark catshark from deep water in the region deserves a second look, a photograph and a place in a museum jar.

• Jaguar Catsharkspecies profile
• Quagga Catsharkspecies profile
• Salamander Sharkspecies profile
• Filetail Catsharkspecies profile
• Ghost Catsharkspecies profile
• Longnose Catsharkspecies profile

Written and reviewed by

SharkSider Editorial Team

A small team focused on researching sharks and making marine biology easy to understand. Every page is reviewed against current species records and the SharkSider attack database, and updated when new incidents or research appear.

Published October 6, 2022 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.