Hingemouth
Small African fish with a unique proboscis-like mouth
The hingemouth is a small freshwater fish native to western Central Africa. It possesses a distinct jaw structure that forms a fleshy proboscis for feeding on detritus. This species survives in low-oxygen swamps by breathing air and holds cultural value in local traditional medicine.
- Unique jaw acts like a proboscis for feeding
- Breathes air to survive in low-oxygen swamps
- Used in Nigerian traditional medicine
- Grows up to 18 cm in length
- Found in Congo and Niger River systems
What it is
The hingemouth is a small fish with an elongated, semi-cylindrical body that reaches lengths of up to 18 cm. Its colour ranges from olive-gray to brown. The most striking feature is its mouth, which points upwards and functions like a proboscis. This structure consists of fleshy lips made of cartilage and connective tissue rather than just bone. The fins are generally colourless, though unpaired fins may show red edges. Small eyes sit on the sides of the head, and large bony plates cover the throat area.
Where it lives
This species inhabits freshwater swamps and slow-moving waters within the Congo and Niger River systems. Its range extends east of the Dahomey Gap in western Central Africa. During dry seasons, it retreats to the bottom of floodplain pools and lagoons. Surveys indicate it is relatively abundant but not dominant in these areas. It prefers deeper, warmer waters with less plant debris on the substrate, such as those found near Lake Tumba.
How it lives
The hingemouth feeds on organic detritus, phytoplankton, and small benthic organisms. Its unique jaw allows fine motor control, enabling it to probe and scrape food from uneven surfaces. It is a facultative air-breather, using its swim bladder as a lung to survive in poorly oxygenated swamps. While likely solitary, it may respond to chemical alarm signals common in its superorder. Little is known about its predators or detailed daily behaviour beyond feeding.
Breeding and life cycle
Reproduction occurs through external fertilization, with females laying eggs that are fertilized by males. Both sexes possess tubercles on their scales and fins, which are more prominent in males. These structures likely assist in maintaining contact during reproduction and may play a role in conflicts between males. Specific details regarding spawning seasons, egg counts, and growth rates remain poorly described in scientific literature.
Fish and people
Local communities have consumed this fish since before Western discovery. In Southwest Nigeria, Ifa practitioners use it in traditional medicine to treat erectile dysfunction and counteract poisoning. It is sourced from traders or caught directly by healers. Although not common in the global aquarium trade, it is occasionally sold to hobbyists. Care information is scarce, making it a rare choice for home tanks despite its unique appearance.
Status and threats
The International Union for Conservation of Nature lists the hingemouth as Least Concern. However, it faces threats from habitat degradation, including deforestation and slash-and-burn agriculture. Pollution is a significant risk, with populations in the Anambra River showing high levels of copper bioaccumulation. Oil spills also affect its habitat in the upper Ekole River. Its specialized anatomy may limit its ability to adapt to rapid environmental changes.
Questions people ask about Hingemouth
What makes the hingemouth's mouth special?
Its jaw joints at the front of the head, allowing the mouth to project forward like a proboscis. This fleshy structure lacks skeletal support in the lower lip and enables precise feeding on small particles.
Can the hingemouth breathe air?
Yes, it is a facultative air-breather. Its swim bladder functions like a lung with alveoli, allowing it to survive in warm, stagnant, and poorly oxygenated swamp waters.
Is the hingemouth used for food?
Yes, locals have consumed it for a long time. It is also caught for traditional medicinal purposes in Nigeria, where it is believed to treat specific health conditions.
Good reading and sources
The facts on this page come from the Wikipedia article "Hingemouth", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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