The clown featherback, clown knife fish, or spotted knife fish, Chitala ornata, is a nocturnal tropical fish with a long, knife-like body. This Fish is a family of bony-tongues Osteoglossiformes. Thai language it’s called Plah Gruy (ปลากราย). The bony-tongues are a primitive but highly successful family of fishes that have been on earth for 200 million years or more. Their shape gives them their common name Knifefish. The other popular common name Featherback comes from the small thin protruding dorsal fin, which is not always so distinct or present in all species, hence the common confusion of some being named Featherback and some Knifefish and vice versa.
The royal knife fish or Indochina featherback, Chitala blanci, is a species of fish in the Notopteridae family found in the Mekong basin in Cambodia, Laos, Thailand, and Vietnam. Thai language it’s called Plah Tong Rai(ปลาตองลาย). Adult size about 10 to 40 inches (25- 50 cm) maximum 100cm
The knife fish is very unique, with normally silvery gray with a long knife-like body (laterally compressed) and a long anal fin that gives these fish their regular name. The Mature clown knife fish normally have five to ten (or more) black spots ringed with white-colored that always decrease in size as the fish grows. These ocellated spots and the lack of faint stripes on the back separate it from Chitala chitala. Juveniles lack the spots but are overall striped. The Royal knife fish are overall striped on their body.

Knife fish Behavior

They are nocturnal and generally driving through the twilight time. They actually hunt live prey and will try any fish that fits into their mouths. Young clown knife fish usually school near water logs and plants for security, whereas more mature specimens usually become territorial and eventually become loners. These fish can also breathe air to survive in stagnant waters and little oxygen. The clown knife fish prefers water around neutral pH and temperature ranging from 75 to 85 °F (24 to 29 °C) pH: 6.0 – 8.0. These fish usually are found in lakes, swamps, and river backwaters. 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. They are generally peaceful and will do well with other fish that are not particularly aggressive and that is too large to fit into its mouth. Do take caution as they have poor eyesight and will sometimes try to eat bigger fish then they can handle. They can ultimately injury or kill a fish they are unable to eat.

In Aquarium

Clown Knife Fish is a captivating species known for its unusual shape and nocturnal lifestyle. Native to the freshwater habitats of Southeast Asia, this fish makes an exciting choice for experienced aquarists, providing a distinctive aquarium experience.

The Clown and Royal knife fish are sold as exotic fishes in pet stores, but they grow much too large for the average home aquarium. The Clown and Royal knife fish Prefer dim lighting and access to refugees in the form of driftwood, large rocks or lengths of plastic piping.

They are jumpers, so the lid should be kept tightly closed.

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.

Despite their intimidating appearance, Clown Knife Fish are generally peaceful. However, their predatory instincts mean smaller tank mates could become an unintended meal. Therefore, careful selection of tank companions of similar size and temperament is crucial.

Maintaining Clown Knife Fish in an Aquarium:

• Tank Size: Clown knife fish are large and can grow up to 1 meter in the wild and about 75cm in captivity. They require a spacious tank – at least 200 gallons for a mature individual.
• Tank Setup: The aquarium should be equipped with plenty of hiding places using rocks, caves, or large driftwood. They prefer low light conditions, so providing a dark substrate with subdued lighting is ideal.
• Water Conditions: Clown knife fish thrive in tropical freshwater with temperatures ranging between 24-28 degrees Celsius and pH levels between 6.0 – 7.0.
• Diet: They are carnivorous and require a diet high in proteins. High-quality pellets, live or frozen foods like bloodworms, earthworms, and feeder fish are ideal.
• Tank Mates: Clown knife fish are generally peaceful, but they are predators and may eat smaller fish. Choose tank mates of similar size and avoid very small or aggressive species.
• Behavior and Temperament: These fish are nocturnal, so they are more active during the night. They can be skittish and appreciate quiet environments.
• Filtration: A high-quality filtration system is needed to maintain water cleanliness, given their carnivorous diet, which can result in a considerable amount of waste.
• Handling Sensitivity: Clown knife fish are known for their sensitivity to water conditions. Regular monitoring of water chemistry is crucial to ensure a healthy environment.
• Breeding: Breeding clown knife fish in home aquariums is very challenging due to their particular requirements, and there is little documented success.
• Lifespan and Health: With proper care and optimal water conditions, clown knife fish can live up to 15 years. Regular water changes and monitoring of water parameters are necessary to prevent disease.

One fascinating aspect of keeping Clown Knife Fish is observing their unusual swimming patterns. Often, they can be seen swimming in a peculiar, backward manner, navigating their environment with an almost eel-like undulation. This, along with their propensity for becoming more active during the evening and night, adds a unique dynamic to the aquarium after dark.

Remember, clown knife fish require an experienced aquarist due to their large size, specific requirements, and sensitive nature. As with all species, understanding and replicating their natural habitat as closely as possible will contribute to their health and longevity.

However, there are many different species of non-native fish in Florida’s waters but one of the more exotic-looking is the Clown Knifefish.

https://www.floridamuseum.ufl.edu/science/florida-invasive-species-clown-knifefish/

Clown Knifefish

Ghost Knifefish (Notopterus notopterus) is the smallest and most common of the Knifefishes in Thailand, Thai language it’s called Plah Chalat (ปลาสลาด), and a very popular food fish served up fried, curried or in spicy soups.