Common Name: Hingemouth Fish
Scientific Name: Phractolaemus ansorgii
Other Names: Hinged Mouth Fish, African Hingemouth
The Hingemouth Fish is a fascinating and rare species known for its elongated body and highly specialized hinged jaw, which allows it to extend its mouth outward to feed. This unique feature makes it one of the most unusual freshwater fish in the aquarium trade. Its body is typically brown or gray with a subtle iridescence, and it has small, rounded fins suited for slow-moving waters. Despite its odd appearance, it is a peaceful species that thrives in well-maintained aquariums with subdued lighting and plenty of hiding spots.
Habitat and Distribution:
Native to West and Central Africa, Phractolaemus ansorgii is found in the Congo, Niger, and other river basins where it inhabits slow-moving, tannin-stained waters, floodplains, and swamps with dense vegetation. It prefers soft, acidic water and areas with fine substrates where it can sift for food. These habitats are often low in oxygen, and like Polypterus, it has a modified swim bladder that allows it to breathe atmospheric air.
Size and Lifespan:
This species grows to about 6-8 inches (15-20 cm) in length. With proper care, it can live for 8-10 years.
Diet and Behavior:
The Hingemouth Fish is an omnivore, feeding primarily on small invertebrates, plankton, and detritus in the wild. In captivity, their diet should include high-quality sinking micro pellets, frozen or live foods such as daphnia, brine shrimp, mosquito larvae, and occasional plant-based foods like spirulina wafers. They are peaceful, slow-moving fish that spend most of their time near the bottom, sifting through the substrate.
Breeding and Reproduction:
Little is known about breeding Phractolaemus ansorgii in captivity. In the wild, they are believed to spawn in seasonal floodplains with soft, acidic water. There are no well-documented cases of successful breeding in home aquariums.
Aquarium Care and Tank Requirements:
A minimum of 40 gallons is required for a small group, but a 55+ gallon tank is ideal. Their ideal tank setup includes a fine sand or smooth gravel substrate, plenty of plants and driftwood for hiding, a well-established biological filtration system to maintain water quality, moderate to low water flow, and dim lighting to replicate their natural environment.
Ideal Tank Mates:
The Hingemouth Fish is peaceful and does well with other calm, non-aggressive species. Suitable tank mates include African Tetras, Congo Tetras, Butterfly Fish, Peaceful Cichlids (such as Pelvicachromis species), Synodontis Catfish, and Ropefish. Avoid overly aggressive or fast-moving species that may outcompete them for food.
Difficulty Level:
Intermediate. They require stable water conditions, a soft substrate, and a diet rich in live or frozen foods.
Water Parameters:
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Temperature: 75-82°F (24-28°C)
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pH: 6.0-7.5
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General Hardness (GH): 3-12 dGH
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Carbonate Hardness (KH): 2-8 dKH
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Ammonia: 0 ppm
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Nitrite: 0 ppm
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Nitrate: <20 ppm (regular water changes required)
Additional Information:
- Their hinged mouth allows them to extend their jaws forward to capture food more efficiently.
- They have a lung-like swim bladder, enabling them to survive in low-oxygen environments.
- Keeping them in groups of three or more encourages natural behaviors and reduces stress.
The Hingemouth Fish is a rare and unusual species that offers a unique addition to an African biotope or specialized aquarium. With the right care, they can thrive and display their fascinating feeding adaptations in captivity.
