Humpback Anglerfish (Melanocetus johnsonii): Deep-Sea Facts

What does a humpback anglerfish look like?

The female humpback anglerfish has a short, rounded, almost ball-shaped body and a very large head. Her mouth is enormous and nearly vertical, lined with long, needle-like teeth that point backward so prey cannot escape. Her skin is soft, dark brown to black and covered with tiny spines, a color that makes her almost invisible in the deep sea.

The most famous feature is the “fishing rod” on top of the head. It is the first spine of the dorsal fin, called the illicium, which has moved forward onto the snout. At its tip sits a bulb called the esca, the lure, which glows. The eyes are small, and the fish has no pelvic fins.

Males look very different. They are tiny, have no lure, and instead have large eyes and big nostrils for finding females. Until the 1920s, male anglerfish were not even recognized as males and were placed in separate groups.

How big is a humpback anglerfish?

The humpback anglerfish is much smaller than most people imagine. Most specimens are only a few centimeters long, and the largest known females measure about 18 cm (7 in), roughly the length of a hand.

The size difference between the sexes is extreme: a large female can be more than five times as long as a male and many times heavier. For a wider look at anglerfish from tiny seadevils to big monkfish, see how big are anglerfish?

Where do humpback anglerfish live?

Humpback anglerfish live in tropical and temperate waters of all the world’s oceans, roughly between 50° north and 50° south. They have been recorded in the Atlantic, Pacific and Indian oceans, including the South and East China seas, and off British Columbia in Canada. In 2014 one turned up in the Ross Sea off Antarctica, found in the stomach of an Antarctic toothfish.

They are midwater fish that float in the open ocean rather than living on the seafloor. Most are found in the twilight zone and upper midnight zone, between about 100 and 1,500 m (330–4,900 ft), where little or no sunlight reaches. A few have been caught as deep as about 4,500 m (14,800 ft). The young live much higher, as larvae in the upper water layers. See our list of deep-sea animals for others that share this world.

What does a humpback anglerfish eat?

The humpback anglerfish is an ambush predator. Instead of chasing food, it hangs almost motionless in the water and waits for prey to come close to its lure. When a fish or shrimp is within reach, it opens its huge mouth and sucks the prey in.

It eats small fish, crustaceans such as shrimp, and squid. Its jaws and stomach can stretch so much that it can swallow animals as big as or bigger than itself. One specimen weighing just 8.8 g (0.3 oz) had three snipe eels weighing 12.3 g (0.4 oz) in its stomach, and a 6.6 cm (2.6 in) individual in a New Zealand museum collection had swallowed a viperfish about 24 cm (9.4 in) long.

This “eat whatever comes” strategy suits the deep sea, where food is scarce. Measurements on live specimens brought to the surface suggest the humpback anglerfish has a very low metabolic rate, even for a deep-sea fish, so it can survive long gaps between meals.

The glowing lure

Only females have a lure. The esca holds a colony of bacteria that produce light, a partnership called symbiosis: the fish gives the bacteria a safe home and nutrients, and the bacteria provide the glow. The bacteria belong to the genus Enterovibrio, relatives of the Vibrio bacteria common in seawater.

The anglerfish can move the illicium with small muscles, twitching the glowing bulb to make it look like a small living creature. In the darkness of the deep sea, where many animals make light and are drawn to it, this is a very effective trap. Read the full story in why do anglerfish have a light? and meet other glowing creatures in our list of bioluminescent animals.

Males, mating and life cycle

Finding a partner is hard when your species is spread thinly through a vast, dark ocean. Male humpback anglerfish use their large nostrils to follow the chemical scent of females and their big eyes to spot them.

In some other deep-sea anglerfish families, the male bites into the female and fuses with her for life. The humpback anglerfish does not do this. Its males attach only temporarily, gripping the female with special toothlike hooks on the snout, and let go after spawning. Both sexes become mature on their own, and males stay free-swimming.

Like other anglerfish, the female probably releases her eggs in a floating gelatinous mass, which the male fertilizes in the water. The larvae drift near the surface, where food is more plentiful, then change into their adult shape and sink into deeper water. Learn more in how do anglerfish mate?

Life in the deep sea

The humpback anglerfish lives in one of the harshest places on Earth. Below a few hundred meters there is no sunlight, the water is cold, often only a few degrees above freezing at 1,000 m (3,300 ft) and below, and the pressure rises by about one atmosphere every 10 m (33 ft). Food is scarce, because only a small share of the life produced in the sunlit surface layer sinks this deep.

The fish is built to save energy. Its bones are thin, its muscles are weak and watery, and its body is soft and loose, which makes it light for its size and close to the density of seawater. That lets it hover with very little effort. It is a weak swimmer that spends most of its time drifting, which also keeps it quiet and hard for prey to notice.

Its small eyes suggest that adult females rely little on sight. In a world lit only by the flashes of other animals, the glowing lure does the work of finding food for her.

Relatives and classification

The humpback anglerfish belongs to the black seadevils, family Melanocetidae, which contains a single genus, Melanocetus, with six known species. It is the most widespread of them. The name Melanocetus combines Greek words for black and a large sea creature.

Black seadevils are one of about 11 families of deep-sea anglerfishes, a group of roughly 170 species that live in open water far from the seafloor. They include footballfishes, dreamers, whipnose anglers and warty seadevils. The wider anglerfish order, Lophiiformes, has more than 300 species and also includes bottom-living relatives such as monkfish, goosefish, frogfish and batfish, which use lures that do not glow.

Discovery and first sightings

The first specimen was found near Madeira, in the eastern Atlantic, in 1863 by the English naturalist James Yate Johnson. The German-born British zoologist Albert Günther described it in 1864 and named it after him.

For over a century the species was known only from dead specimens hauled up in nets. In 2014 the Monterey Bay Aquarium Research Institute (MBARI) filmed a female alive at about 600 m (1,900 ft) in Monterey Canyon off California with a remotely operated vehicle, believed to be the first video of this species in its natural habitat. In February 2025, divers and researchers photographed a live female swimming at the surface in daylight off Tenerife in the Canary Islands. It is not known why it had come up so far; deep-sea fish seen at the surface are often ill or disoriented.

Predators, threats and conservation

Little is known about what eats humpback anglerfish, but they are found in the stomachs of larger deep-sea predators, such as the Antarctic toothfish. Deep-sea anglerfish in general are eaten by fish such as lancetfish, black scabbardfish and large tunas, and bigger anglerfish have been found in sperm whale stomachs.

The IUCN Red List classifies the humpback anglerfish as Least Concern (assessed in 2013). It is not fished for food, but some are caught accidentally in deep-water trawls, and scientists note that bycatch could increase as fishing moves into deeper water.

Myths and facts

Myth: anglerfish are huge sea monsters. The humpback anglerfish fits in the palm of your hand. Close-up photos and films such as Pixar’s Finding Nemo (2003), whose deep-sea anglerfish resembles a black seadevil, make it look far bigger.

Myth: all male anglerfish fuse to females. Permanent fusion happens only in some families; humpback anglerfish males attach briefly and swim away.

Fact: the fish does not make its own light. The glow of the lure comes from bacteria living inside it.