The Clown Knife has the typical knifefish body shape, flat and elongated with an arched back. Its anal fin and caudal fin (tail fin) are joined, giving it a long continuous fin along the underside. This fin undulates, allowing it to move either forward or backward, making it a very graceful swimmer.

Clown Knife Fish are suggested for an aquarist with some fish-keeping experience. They can be hard to get adjusted to a new tank and this often results in death. This fish can grow to a substantial size, reaching about 3 1/2 feet (100 cm) in the wild. Specimens raised in the aquarium, however, generally won’t grow much larger than 10 – 20 inches (25 to 50 cm). This is still a large fish, but since they are not particularly active they do not need as large of a tank as you might think. An adult can be comfortably housed in a 200-gallon (757 l) aquarium. Being nocturnal they need places to retreat during the day as well as open areas for swimming. Once acclimated, they are very hardy fish.