India, Pakistan, Bangladesh, Nepal, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Indonesia.
Inhabits slow moving areas of streams and canals, and semi-permanent bodies of water, such as lakes and ponds. Migrates to flooded areas to breed during the rainy season and has also been recorded in brackish waters, although it is doubtful the fish could remain under these conditions for long.
Maximum Standard Length
24″ (60cm) in nature, although aquarium specimens measuring over 14″ (35cm) are considered large.
Aquarium SizeTop ↑
60″ x 24″ x 24″ (150cm x 60cm x 60cm) – 565 litres.
Requires an aquarium with many hiding places and sheltered areas. Areas of dense planting, large chunks of bogwood, rock piles and lengths of plastic piping are possible alternatives. It is a largely nocturnal species and prefers dim lighting. This can be further diffused with the addition of floating vegetation. In the right setting the fish will often be seen during daylight hours.
Temperature: 75-82°F (24-28°C)
Prefers frozen and live foods, especially earthworms and bloodworm, although some learn to accept dried alternatives.
Behaviour and CompatibilityTop ↑
A somewhat belligerent species that will also eat smaller tankmates, although it is not usually aggressive towards bigger fish than itself. Potential tankmates could include larger barbs, characins, Loricariids and robust cichlids.
It’s very territorial and nasty with conspecifics, however and should be kept as a single specimen, unless the tank is very large.
No external sexual differences.
Has been achieved in aquaria, but not with any great regularity. The fish is mass-produced on commercial fish farms in some of its native countries. In nature, the fish are seasonal spawners, breeding during the rainy season. Eggs are deposited in clumps onto aquatic vegetation. However aquarium reports seem to suggest that the eggs were simply laid directly onto the substrate or decor. These are then guarded by the male for around 2 weeks, until they hatch. Once they’re free-swimming, the young can be raised on the usual fare of brine shrimp nauplii, microworm etc. A successful breeding attempt would surely require an enormous aquarium, given the intolerance of this fish for its own kind. Some kind of spawning trigger, such as a large influx of cool water may also be required.
N. notopterus is an important food fish in many of its native countries. Soup made from it is said to have health-giving properties and bizarrely is often given to people suffering from measles. It’s not often seen for sale in the hobby, although most decent shops should be able to get hold of some on request. An albino variety is also occasionally available. It looks superficially similar to the closely related African knifefish, Xenomystus nigri, but can be distinguished by its larger adult size and the presence of a dorsal fin, which is absent in X. nigri.
Like other members of the family Notopteridae, this species differs from Gymnotiform knifefish in that its anal and caudal fins are fused together into one long, undulating fin running along the underside of the fish. It should also be noted that this is a scaleless species and is very sensitive to medications added to the aquarium. Halve the dose of any treatment required in its tank and avoid the use of salt altogether.