Arnoldichthys spilopterus, the Niger tetra, is a characin endemic to Nigeria. It is the only member of its genus.
Arnoldichthys spilopterus is a tropical freshwater species found only in a limited number of locations in Nigeria (Ogun and Niger rivers). Males are on average 9.6cm (03.8inches) long. Its diet consists of worms, insects, and crustaceans. Females in captivity can lay about 1,000 eggs, which hatch within 30–34 hours.
This species is currently classified as endangered by the IUCN due to its limited range coupled with losses to the aquarium trade and ongoing habitat degradation.