The Royal
Knifefish is a fish from Malam Jungle. They are extremely common, contrary to
the name, which might make fishers think that they are less common. They are
caught by casting S-M from the pier of around it. It is an easy catch to hit
and reel in.
In the aquarium
The royal knifefish, often sold as the royal clown
knifefish, is occasionally sold in the aquarium trade.
Distribution
Endemic to the Mekong river drainage in Laos, Thailand,
Vietnam, and Cambodia, including the Mekong delta region and Tonlé Sap lake
system.Type locality is ‘Beng-Cha, upper Mekong River, northern
Cambodia’.
Habitat
Mostly recorded from the Mekong main channel and lower parts
of certain tributaries, where it displays a preference for rocky habitats such as
deep pools and rapids, typically with moderate to fast-flowing water. Moves
into areas of flooded forest to spawn.
It is thought to be threatened by dam construction and other
anthropogenic habitat alterations.
Maximum Standard Length
800 – 1200 mm.
Aquarium Size
Suitable only for public installations or the very largest,
highly-specialised private aquaria.
Maintenance
Prefers dim lighting and access to refuges in the form of
driftwood, large rocks or lengths of plastic piping.
A large, mature filter system, rigorous maintenance regime
comprising weekly water changes of 50-70% tank volume, and provision of
highly-oxygenated water with a degree of movement should be considered
mandatory.
Diet
An obligate, typically nocturnal, predator feeding on
smaller fishes, crustaceans and other invertebrates in nature but in most cases
adapting well to dead alternatives in captivity.
Young fish can be offered chironomid larvae (bloodworm),
small earthworms, chopped prawn and suchlike while adults will accept strips of
fish flesh, whole prawns/shrimp, mussels, live river shrimp, larger earthworms,
etc., as well as dried pellets although the latter should not form the staple
diet.
This species should not be fed mammalian or avian meat such
as beef heart or chicken since some of the lipids contained in these cannot be
properly metabolised by the fish and may cause excess fat deposits and even
organ degeneration.
Similarly there is no benefit in the use of ‘feeder’ fish
such as livebearers or small goldfish which carry with them the risk of
parasite or disease introduction and at any rate tend not have a high
nutritional value unless properly conditioned beforehand.
Behaviour and Compatibility
Relatively peaceful with fishes too large to be considered
prey but can be territorial with conspecifics and other similarly-shaped
species, especially if space is at a premium.
Sexual Dimorphism
Unreported in captivity but in nature male individuals
contruct nests from branches and leaves and remains to guard the eggs and fry
post-spawning, which takes place in areas of flooded forest during the wet season.
Notes
This species is also referred to as ‘royal knifefish’ in the
aquarium trade although it arguably has no place in the ornamental hobby given
its adult size and specialised requirements.
It can be distinguished from congeners by presence of many
small, dark spots on the anterior portion of the body which merge to form
oblique, irregular stripes extending onto the anal and caudal fins posteriorly.
Notopterids are distributed in Africa and Southeast Asia and
all possess an elongated anal-fin which is continuous with the caudal-fin, a
‘humped’ appearance, very small scales, plus the ability to breathe atmospheric
air.
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