Astronesthes niger, commonly known as snaggletooth, is a species of small, deep sea fish in the family Stomiidae.

Astronesthes niger is a slender, somewhat elongate, black fish with a large mouth, fang-like teeth, and a long barbel on its chin tipped by a knob.

There are two longitudinal rows of photophores on either flank and there are luminous patches in front of the eye, above the nostrils, above the eye, and a large patch above the pectoral fin.

[2] The species is found in the mesopelagic zone of the tropical and subtropical Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico, between about 40°N and the equator.

Astronesthes niger is a predator and feeds on krill, amphipods and lanternfishes.