| Name | Arowana | Diet | Carnivorous |
| Scientific name | Osteoglossinae | Weight | 2.5–17.2 kilograms (5.5–38 pounds) |
| Pronunciation | Arow-ana | Length | 2–3 meters (6.6–9.9 feet) |
| Classification | Actinopterygii, Osteoglossiformes, Osteoglossidae | Location | South America, Australia and Asia |
The Arowana
The arowana is a unique family of fish native to Asia, South America, and Australia.
This freshwater fish is also commonly referred to as the bony-tongue fish because of the toothed bone on its tongue.
The arowana has a primitive appearance and several unique features.
This isn’t surprising because this fish family has been around for a long time.
They evolved as far back as the Jurassic Period, about 170 million years ago.
The primitive features of this fish give it a monster-like appearance.
Yet the arowana is one of the most coveted fish species worldwide and is commonly kept as a pet.
Read on as we explore all the fascinating features of this unique family of fish, including their appearance, habitats, diet, conservation status, and unique adaptations.
Taxonomy and Classification
Arowana is the common name for a group of freshwater fish that belong to the Osteoglossinae subfamily.
This group is a subdivision of the larger Osteoglossidae family.
The family includes the arowanas and their close relatives, the arapaimas (subfamily Arapaiminae).
Some members of the Arapaiminae subfamily are sometimes erroneously referred to as arowanas because of their close similarities to the actual arowanas.
But this is inaccurate.
Currently, the arowana subfamily only has two living genera: Scleropages and Osteoglossum.
Members of the Scleropages genus are native to Asia and Australia, while the Osteoglossum is only found in the freshwater system of South America.
Cumulatively, about nine species of fish are in the arowana subfamily (seven species in the Scleropages genus and two species in the Osteoglossum).
Some of the most popular species include:
- Scleropages formosus (green arowana)
- Scleropages leichardti (southern Saratoga)
- Scleropages jardinii (Australian bonytongue)
- Osteoglossum bicirrhosum (silver arowana)
- Osteoglossum ferreira (black arowana)
The Osteoglossinae subfamily evolved several million years ago — as far back as the Jurassic.
Species in the Osteoglossum genus diverged from the same common ancestors as their Asian and Australian relatives (the Scleropages arowanas) during the Middle Jurassic Period, about 170 million years ago.
Physical Characteristics
The arowana is a bony fish with an elongated body.
Their distinctive cylindrical and streamlined appearance gives them an eel-like appearance.
The elongated body of this fish is covered by large scales with a mosaic pattern.
Arowanas have a bony head with its mouth at the top of its body.
The fish has two barbels on its lower jaws, which serve the purpose of detecting vibrations in the water.
Arowana’s mouth opens wide into three pieces.
Arowanas are relatively large freshwater fish.
The size can vary among species, but they typically grow to a length of about two to three feet in captivity.
Some individuals may grow even larger in the right conditions.
For instance, there are reports of some silver arowanas growing to a length of up to 1.2 meters (3.9 feet).
Arowanas have dorsal and anal fins made up of long, soft rays, but their pectoral and ventral fins are small.
The arowanas and their relatives in the Osteoglossidae family are often called bonytongues (although the name applies more formally to the Arapaimas).
They got this nickname because most of their teeth are located on their tongue.
Some species also have teeth on the roof of their mouth and in their pharynx.
Arowana scales are often iridescent, which contributes to their beautiful appearance.
Fish in this family are known for their striking coloration, which varies from one species to the other and may also change with age.
Some of the most common color patterns for fish in this family include silver, green, and blue hues, with contrasting colors along the lateral line.
The silver arowana, for instance, typically has a silver body with dark spots on its scales.
Some rare species may also exhibit red or golden coloration.
Habitat and Distribution
The arowana is a type of freshwater fish.
It is mainly found in slow-moving or still waters within streams, rivers, and other freshwater systems.
This fish prefers areas of the water near dense vegetation, submerged tree branches, and overhanging vegetation.
These areas provide cover for them and opportunities to hunt for prey.
Arowanas are adaptable to varying water conditions.
Some species can be found in flooded forests, blackwater, and whitewater environments, demonstrating their adaptability.
This fish is native to South America, Asia, and Australia.
South American arowana species are mainly found in the tropical waters of the Amazon, Essequibo, and Oyapock River basins.
They’re generally absent from the Rio Negro Basin, although some species of silver and black arowanas live in the Branco River, which is a part of the basin.
Asian varieties are found in Thailand, Southern Vietnam, Cambodia, Sumatra, West Borneo, and the Malay Peninsula.
In Australia, the spotted bonytongue lives in the waters of the Fitzroy River.
The Australian bonytongue is also found in the drainage system of the Gulf of Carpentaria and other freshwater systems throughout northern Queensland.
Behavior and Social Structure
The arowana is an active and agile fish.
They live near the water surface, where they typically hunt for food.
Some species have been known to leap out of the water to catch prey at heights of up to two meters (six feet) from the water surface.
This ability to jump out of the water has earned them the nickname “water monkeys.”
The agility of this fish also makes it challenging to keep as a pet since they require a wide living space and are picky eaters.
Although they can live with other fish in aquariums, arowanas are famous for their aggressive behavior and personality.
Ideally, each fish will need at least 300 gallons of water, and the tank must be covered with a solid lid.
In the wild, arowanas are solitary and territorial.
Each individual will establish territory within a defined area and defend it aggressively from other arowanas or intruding fish.
They do not migrate since they generally prefer to remain within their defined territories.
Diet and Feeding
The arowana is a carnivorous fish.
They are ambush predators known to attack fish and other prey from below.
In the wild, they have a varied diet, practically feeding on any prey they can get their mouth around.
The arowana can open its mouth wide like a trap door, and this puts most animals in their habitat on the menu.
They feed on small fish, insects, and crustaceans, which they typically hunt near the water surface.
“Frogs, birds, bats, and even snakes have been found in the bellies of some individuals, showcasing their diverse diet.
Arowanas have a sharp eyesight and can spot prey in and outside the water.
One of the unique attributes of this fish is their ability to leap out of the water to catch food.
When they spot potential prey (an insect hovering above the water or a bird perched in the tree branches above), the arowana can leap up to two meters above the water with great agility.
The fish uses its mouth and sharp teeth to trap and kill prey.
Due to their aggressive hunting habits, people typically don’t keep aquarium species with other fish that can fit into their mouths.
Pet arowanas are often fed with fish pellets.
You can include meaty supplements like krill and shrimp in their diet.
Reproduction and Life Cycle
The spawning season for arowanas typically coincides with the start of the flooding season.
This is typically from December to January in most places.
Females arowanas produce a small number of large eggs (up to 58), which the male then fertilizes.
The fish exhibit elaborate courtship behavior before mating.
The male and female swim alongside each other or in circles, with the male chasing the female.
Some species also display vibrant colors and patterns during this courtship.
Courtship may go on for about one to two weeks before spawning occurs.
Arowanas generally exhibit parental care.
After fertilizing the eggs, the male picks them up in his mouth.
The eggs hatch after about a week, but the hatchlings will remain in the male’s mouth for about seven to eight weeks after hatching.
They may take short trips outside his mouth to investigate their environment and feed on tiny aquatic organisms nearby, but they will typically return until they mature.
Arowanas grow very slowly.
Unlike other fish species that may start reproducing at about six months, arowanas don’t mature until they’re about three to four years old.
Individuals may live for up to 10 years in captivity.
Ecological Role and Interactions
The arowana is a large predator and one of the top predators in the freshwater ecosystem where it lives.
This skilled hunter is at the top of the aquatic food chain, preying on various species, including smaller fish, insects, crustaceans, and terrestrial vertebrates.
Arowanas help control the populations of prey species within their ecosystem.
By controlling or limiting the abundance of certain species, arowanas help maintain the balance and diversity of the freshwater environment.
While they are predators, arowanas (especially juveniles) are an essential food source for larger predatory animals within their ecosystem, contributing to the food web and nutrient cycling.
Arowanas do not typically interact with other species within their ecosystem.
This limits the chances of forming mutualistic or symbiotic relationships with other species.
They are solitary and tend to be aggressive towards organisms.
In aquariums, you can pair this fish with others such as the pacu, clown knifefish, green terrors, gar, siamese tigerfish, and other aggressive species that they are unlikely to prey on.
You should keep Australian species alone in tanks.
Conservation Status and Threats
The IUCN Red List lists most arowana species as “Least Concern,” indicating they maintain a relatively stable population.
However, a few species, like the Scleropages formosus (Asian arowana or golden arowana) and Scleropages leichardti (southern saratoga), are listed as Endangered and Near Threatened, respectively.
This means they are at risk of going extinct due to their dwindling population in the wild.
The destruction of their natural habitat and the pet trade capture pose the biggest threats to arowana species.
This has caused a steep decline in their populations in the wild.
In fact, some species, such as the Asian arowana, are more abundant in aquariums than they are in the wild.
People consider them one of the most prized aquarium fishes in the world.
In many places, people have converted the swamp habitats this fish prefers into agricultural land.
Their rapidly shrinking habitats and increased demons in the pet trade have made it difficult for the endangered and threatened species to recover in the wild despite best efforts to protect them.
Unique Adaptations and Survival Strategies
People know Arowanas for their extraordinary jumping ability.
They can leap several feet above the water’s surface to catch prey or escape from predators.
This adaptation is a survival strategy that allows them to quickly respond to feeding above the water’s surface.
Another unique adaptation demonstrated by this fish species is their bony tongue.
Their tongue has teeth-like structures that effectively grasp prey, especially small fish and insects.
Although they have gills, arowanas are facultative air breathers.
They can obtain oxygen directly from the air, especially when the water they inhabit has low dissolved oxygen (hypoxic).
The swim bladder of this fish has capillaries similar to lung tissues that help it absorb oxygen from the air.
The unique coloration of most arowana species helps them blend in perfectly with the rest of their environment when viewed from above or below.
This camouflage aids in ambushing prey or hiding from potential threats within their environment.
Cultural Significance and Human Interactions
The arowana is popular locally in Asia, South America, and Australia.
In China, people also know the species as the “dragon fish” because its shiny, scaly armor resembles the typical description of the Chinese dragon.
Many consider the dragonfish a symbol of luck, prosperity, and wealth.
These beliefs about the arowana are part of what fuels their popularity as pet fish in Asia.
Rich Asian men consider the dragonfish a symbol of wealth.
The Asian arowana is one of the most expensive pet fish species in the world.
In one instance, someone sold a rare albino arowana for a record $300,000.
Since 2012, the arowana pet trade has been generating up to US$200 million annually and isn’t slowing down.
People keep all nine arowana species as pets.
However, one of the popular pet species, the African arowana, isn’t really an arowana despite its similarity to them.
People target Arowanas for their attractive scales, meat, and fins, which they use for food and traditional medicine in some places.
In Brazil, people favor adult silver arowana as a delicacy, while in Colombia, they often catch juveniles for the pet trade.
This shared use of the species is a common cause of conflicts between the two countries.
Future Prospects and Research
Due to concerns about their population and conservation status, there are initiatives to breed arowana in captivity.
Successfully doing this will reduce pressures on wild populations of this species.
Researchers are also carrying out projects to investigate the biology, behavior, and habitat of this species, which are essential for its conservation.
Research of this nature will aid in developing conservation plans and management strategies by governments and conservationists.
Some regions use Arowanas in traditional medicine.
Scientists may explore the potential medicinal properties of bioactive compounds within the fish, which could have implications for medical advancements in the future.
Conclusion
The arowana is a fascinating freshwater fish that lives in a wide range of environments in Asia, Australia, and South America.
This fish has a bony tongue and can uniquely jump out of the water to catch aerial prey.
The arowana has a long, eel-like body with a striking coloration.
This unique appearance makes it one of the most popular ornamental fish species.
People in Asia have nicknamed it the dragonfish and highly seek it as a pet.
While the wild harbors some endangered species of this fish, the aquarium hobby industry continues to grow its capture and sale.
Without urgent intervention, arowana individuals in captivity may one day outnumber, putting these species at risk of extinction.
Sources:
- https://en.wikipedia.org/wiki/Arowana
- https://nationalzoo.si.edu/animals/silver-arowana
- https://livingplanetaquarium.org/animal/asian-arowana/
- https://biologydictionary.net/arowana/
- https://www.thesprucepets.com/arowana-fish-species-profile-5077431
- https://cites.org/eng/gallery/species/fish/golden_arowana.html
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