The Clown Knifefish ( Chitala ornata ) is a captivating and exotic freshwater fish that has captured the interest of aquarists around the world. Also known as the clown featherback or spotted knifefish, the clown knife fish can grow quite large and is a highly sought-after game fish. Known for their unique appearance and nocturnal behavior, these fish can make a striking addition to your home aquarium, provided you can meet their specific needs.
An Overview of the Clown Knifefish
Native to the slow-moving rivers and lakes of Southeast Asia (Cambodia, Thailand, and Vietnam), the clown knifefish belongs to the Notopteridae family. This species has also been introduced to other regions through the aquarium trade and is now considered an invasive species in some areas, such as South Florida.
Clown knifefish are generally silver with a green tinge. The most striking feature is the circular markings along the middle area of the fish (ocellaris). The ollecari may increase in size and number as the fish grows. The clown knifefish are flat, silvery fish with an elongated body, a humpback, and a long anal fin that gives the knifefish its common name. They have a tiny dorsal fin and 5-10 black spots ringed with white that distinguishes them from all other fish. Juveniles possess dark vertical bands instead of spots. They have two nasal tentacles located above their toothed mouth. They have no ventral fins but a flag-like dorsal fin in the center of the body.
Adults can grow up to 4' in the wild but rarely grow over 20 inches in length in a tank, although they can reach lengths of up to 36". One of the most striking features of this fish is its elongated, knife-like body with a distinctive silver-grey color and black "eye" spots running down its back. They are quite remarkable to watch when they swim, as they are just as comfortable swimming backwards as they are going forwards, and they are amazingly flexible. When changing direction, they can turn within their own body length and often seem as though they have no backbone. Although they are very high through the body, they are very narrow widthways.
Housing Requirements
Due to their large adult size, reaching up to 120 cm (almost 4 feet) in length, they should only be housed if you have a very large aquarium. Clown Knifefish are best suited to public aquariums unless you are very experienced and have the facilities to house these fish in the correct conditions. Given their potential size, clown knifefish require a spacious aquarium of at least 200 gallons or larger. The first thing you need to think of when it comes to this fish is that it can reach an enormous size, even in the home aquarium. They are often offered for sale as small as 3", and a lot of fish stores seem to forget to mention to the prospective owner that this cute little wiggler can reach lengths of up to 36".
Read also: Feeding Clown Loaches
They do better with open swimming space but are adept at negotiating obstacles such as plants and piles of rock.
Solitary or Community?
The Clown Knife Fish does well if kept singly; they tend to not get along very well with their own kind. When young, these fish are comfortable in groups, but as they mature, they much prefer to live singly. Adult specimens will not tolerate another Clown Knife or similar species in their tank, though, there has been success with raising young Clown Knives together to adulthood.
You can keep them with large catfish because they will not bother one another. Clown Knives tolerate large tankmates quite well, often ignoring attempts by territorial cichlids to chase them off. Depending on the species of knifefish you keep, a few compatible fish include silver dollars, tinfoil barbs, angelfish, large cichlids, larger Gouramis, and Synodontis catfish.
Clown Knife Fish have bigger mouths than you might realize, so be careful not to keep fish that are small enough to fit in their mouth. They also cannot be kept with smaller fish of any kind, as anything small enough to fit in their mouth will be considered food, and they will often take a snap at larger fish, just on the off chance they may get a meal out of it.
Tank Setup
They prefer dim lighting and well-oxygenated water, and some water flow should be provided. Water quality should be pristine, with undetectable ammonia and nitrites, and nitrates below 20 ppm. pH should be between 7.0 and 8.0, with alkalinity between 5° and 10° (90 ppm to 180 ppm). Temperature should be maintained between 75° and 80° F. If the aquarium is kept in rooms below 75°, use an Aqueon Aquarium Heater to maintain the correct temperature.
Read also: Habitat and Care for Featherbacks
Due to their nocturnal nature, they need a place to hide during the day. A piece of pipe or a cave where they can get away from the light. Without this, they can become stressed very easily and will try to fit themselves into any dark space they can find, often causing damage to themselves. Plenty of cover in the form of tall plants and driftwood, as well as caves and grottos, should be provided to help knifefish feel safe. When keeping large knives, use artificial plants with weighted bases to prevent them from being uprooted. Lighting should be subdued to encourage them to come out during the day, and a secure cover should be used to keep them from jumping out of the aquarium. They prefer a neutral pH and softer water, but larger fish can adapt to a higher pH and hard water.
Knifefish are sensitive to many medications, so the use of a UV sterilizer is recommended to prevent disease rather than having to resort to chemicals after a disease outbreak. Maintain good filtration and change 10% of the water every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner. Do not forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Diet and Feeding
The Clown Knife Fish is a carnivore that can be fed a variety of meaty foods such as worms, crustaceans, and insects. In their natural habitat, they are exclusive piscivores, and this can become a problem in the home aquarium. It is best to try to adapt knifefish to pellet and other dry foods as soon as possible, but many will show a preference for frozen or even live foods despite the aquarist's best efforts. Avoid the use of feeder goldfish or livebearers as they may carry diseases and are not nutritionally suitable.
They can be trained to accept a variety of store-bought foods that contain other much-needed nutrients. If you start young enough, they can be trained to eat pellets and some frozen foods, but this cannot be guaranteed, so a supply of healthy live feeder fish is usually required, especially in the beginning when you bring them home from the LFS. This supply can consist of pretty much anything the fish can fit in its mouth, Goldfish, Buenos Aires Tetras, Neon Tetras, small Convicts, Guppys, etc. Some other foods that will sometimes be accepted are pieces of prawn, shellfish, and some meaty foods such as beef heart, although animal proteins are not considered very healthy for them and should only be fed occasionally. Vary your Clown Knife's diet as soon as possible. Don't let your Knife get locked onto ONE food type.
Aqueon Tropical Granules, Betta Treat Shrimp Pellets, and Cichlid Pellets are good choices for small to medium-sized knifefish, while Monster Fish Medley can be fed to larger species like clown, African, and featherfin knives. Small amounts of food can be fed after the aquarium light is turned off to accommodate their nocturnal feeding behavior. Remove any uneaten food in the morning to avoid water quality problems. For best results, rotate their diet daily and feed only what they can consume in 2 to 3 minutes, once or twice a day.
Read also: Duane Dieter CQD Knife
Behavior and Compatibility
The Clown Knife Fish is nocturnal, although they sometimes come out during the day. Due to their nocturnal nature, lighting should be subdued to encourage them to come out during the day. They tend to be quite shy and skittish fish which can be easily startled when surprised. Unlike their South American name sake, they have very good eye sight, which enables them to be highly skilled predators. They are ambush predators so while hunting, they like to approach small fish from behind, sneaking up very slowly, then pouncing and engulfing their prey whole in their enormous mouths.
Most knifefish are nocturnal and tend to be shy, especially when first introduced to an aquarium. As they settle into their new homes, they often become more outgoing during daylight hours, particularly around feeding time. They tend to be territorial and can be aggressive toward each other or closely related species, so they are best kept one to an aquarium with other peaceful fish that are too large to be eaten. This is especially important with clown knives, which not only get extremely large but are highly predatory.
Potential Health Issues
They are very hardy fish once they reach a certain size but can be sensitive to water conditions and some medications when they are smaller than 9 or 10". Knifefish are scaleless and extremely sensitive to poor water conditions. Clown knifefish are generally hardy, but like all aquarium fish, they can be prone to certain health issues. Maintain a clean environment and monitor water parameters regularly to prevent stress and the onset of diseases such as ich or fin rot. If any health issues arise, consult an aquatic veterinarian for guidance.
Breeding
Captive breeding is possible but this probably won't happen unless the fish are kept in a very large tank, in this case, that means 500 gallons or more. Breeding/Reproduction: Captive breeding is possible but this probably won't happen unless the fish are kept in a very large tank, in this case, that means 500 gallons or more. They are usually bred in ponds. It is known that in the wild the female deposits the eggs rather than scattering them on flat surfaces, once the eggs are laid it is the male that assumes all the parental duties. The male Clown Knife Fish stands guard over the eggs and the young.
Spawning reportedly occurs in spring when the females lay thousands of eggs each on the substrate or piece of wood; males care for the eggs by fanning them with his tail, keeping them aerated and silt-free. In addition, the males protect the fry once hatched. They usually start to spawn at the beginning of the rainy season in grassy, flooded areas. In some regions, clown knife fish spawn when there are three consecutive days of rain when they seek shelter in water hyacinths.
The pair will usually lay their eggs on a flat rock with floating plants as cover. The male will aggressively guard them until they hatch in 6 or 7 days. The fry should be moved into a rearing tank and fed baby brine shrimp until they are large enough to take other foods.