Upside-down catfish, Synodontis nigriventris, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of catfish

Catfish

Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

. It is particularly noteworthy because of its habit of swimming upside down most of the time. Upside-down catfish originate from the Central Congo basin

Congo River

The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...

 of Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

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Appearance and anatomy

Upside-down catfish are small, reaching a maximum of 9.6 centimetres (4 in). Like other members of the mochikidae family, they have large eyes, a large dorsal fin and three pair of barbels. Upside-down catfish are adapted to spend most of their time upside-down. This is reflected in the fish's pigmentation—their bellies are darker than their backs, a form of countershading

Countershading

Countershading, or Thayer's Law, is a form of camouflage. Countershading, in which an animal’s pigmentation is darker dorsally, is often thought to have an adaptive effect of reducing conspicuous shadows cast on the ventral region of an animal’s body...

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Ecology

These fish are mostly nocturnal, and feed on insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, and plant matter. These fish lay eggs. The young fish do not swim upside-down until they are about two months old.

In the aquarium

The upside-down catfish is well suited to aquariums because of its small size (typically 9 or 10 cm or less) and peaceful demeanor. They should be kept in schools of 3 minimum for best effect. They should be fed a variety of good quality flake food, tablet food, frozen bloodworm and livefood as daphnia. Provide caves or ledges to them to loaf in.