Blackmouth catshark
Galeus melastomus
A small, marbled shark of the deep slope that almost no visitor will ever see, so no trip can promise a meeting.
Least Concern (IUCN, 2020) means it is not at high risk of extinction at the moment, even though many are caught and discarded in trawls.
Length
Up to about 90 cm (35 in) for females and 75 cm (30 in) for males (FishBase); Atlantic animals grow larger than Mediterranean ones
Weight
Up to about 1.4 kg (3.1 lb) reported by FishBase; typical weight is not given
Next to a person
Roughly the length of a person's arm at the small end, and up to about half the height of an adult at the large end. It weighs about as much as a bag and a half of sugar.
What it eats
Mostly animals on or near the sea floor, such as shrimps, krill and squid or octopus. It also eats small fish such as lanternfishes. Young sharks eat more small crustaceans, while adults take larger fish.
Around people
Deep, rarely met
How it lives
It lays eggs. Females can carry up to 13 developing eggs at once, though 1 to 4 per side is usual, and egg cases are vase-shaped and golden brown when laid. In the Ionian Sea, FishBase reports egg laying at 200 to 600 m between February and September. FishBase lists depths of 55 to 1,873 m, usually 150 to 1,200 m, and a low resilience, meaning a population can take 4.5 to 14 years to double.
Where it goes
It lives on the sea floor of the continental slope and is a bottom dweller rather than a long-distance traveller. Sources describe its range as the north-east Atlantic and the Mediterranean, and no migration routes are given. Larger animals tend to be found in the Atlantic than in the Mediterranean.
We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.
Populations
Global: Least Concern (IUCN, assessed 2020). It is caught in large numbers as bycatch in bottom trawls and on longlines, and is mostly thrown back because it has low value. In Mediterranean surveys off Sicily, most sampled sharks were immature. The sources read give no total population number.
Meet it respectfully
Visitors almost never meet this shark in the wild, because it lives hundreds of metres down on muddy slopes. If you ever see one on a fishing boat, leave the handling to the crew and follow their advice. Never chase, touch, feed or bait any wildlife, and follow your guide and local rules.
Fun fact
Tap the bulb to light it up.
The inside of its mouth is black, which gives the shark its name.
It lays eggs, and females can hold up to 13 developing eggs at a time.
It is usually found 150 to 1,200 m down, far deeper than most people ever go.
Blackmouth catshark in the Ocean Atlas
Places we have researched where this animal is recorded. It is never guaranteed, and some places are for watching from the boat only.
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Algeria
France
Ireland
Italy
Norway
Portugal
Spain
United KingdomSources for this page
- FishBase, 2025
- Wikipedia, Blackmouth catshark
- Mediterranean Marine Science, Strait of Sicily study
- GBIF / IUCN Red List category, 2020
Facts checked 5 October 2026. Photos: Unsplash licence, or Creative Commons as shown on each photo.
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