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Region: Africa Class: Osteichthyes Order: Osteoglossiformes Family: Osteoglossidae Genus: Heterotis Scientific Name: Heterotis niloticus
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Description:
They are large fish, reaching a maximum length of 1 m. The body is somewhat elongated and covered with large scales. The dorsal and anal fins are placed far back on the body, and about equal in size. The name Osteoglossidae literally means "bony tongue", as these fish have a toothed tongue.
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Distribution:
Africa, widely spread in the Upper Nile, as well as the Chad, Niger and Senegal rivers.
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Habitat:
Found in rivers, moving waters and swamps.
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Food:
The African bonytongue is the only member of the Osteoglossidae that is not a predator. Despite their large size, these fishes are filter feeders. They filter food particles out of the water as well as from the sediments. Their diet consists of zooplankton (shrimp, etc.) and phytoplankton (suspended algae, etc.).
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Reproduction and Development:
In the shallow waters of swamps (about 20 to 60 cm deep), the male constructs a cylindrical nest about 1 m in diameter. The nest consists of a mud bottom, with walls formed out of plant material up to 20 cm thick. The top of the walls project above the surface of the water. After spawning takes place, the fish leave the nest by way of a hole in the wall. After approximately 5 days, the fry emerge from the nest and are guarded by the male.
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Adaptations:
Of all bonytongues, only the African fish have adaptations for filter feeding. Their fourth gill arch is modified into a spiral-shaped filtering apparatus. An organ secretes mucus across this filter, in which food particles are trapped and then swallowed. In addition, the bonytongues are also able to breathe air, which allows them to inhabit oxygen poor waters common in the tropics, and especially in their nesting sites. Their swimbladder is comparable to a lung, as it is highly vascularized for oxygen absorption. The fish swim to the surface and gulp air which can be forced into the swimbladder. The fry also adapted to living in the poorly oxygenated waters of the swamps. They have external branched gill which increase the surface area for oxygen absorption and gas exchange.
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Threats to Survival:
None
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Status:
Common
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Zoo Diet:
Brine shrimp, bloodworms, tubifex worms, beef heart gel, fish gel.
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Animal Fact Sheet
The New Tundra Trek