Like all aquarium fish, the natural habitat of Arowanas dictates how they may be best cared for in captivity. Although Arowanas have been kept in captivity for decades, this is but a drop in the bucket in terms of their existence in the wild.
Arowanas are considered “living fossils,” and their presence has been established at 60 million years ago or more. Their ancestral history dates back more than 130 million years. The longevity and freshwater evolution of the 7 Arowana species points to their successful adaptation to their environment.
As much as possible, Arowanas natural habitat must be mimicked for their success in captivity. As closed systems, it is of course impossible to leave Arowana care to “natural” processes in the aquarium. But it is possible to let their natural preferences guide how we care for them to best support their health and promote their well-being.
From Nature to Nurture
Most Arowana fans know that the asian varieties are native to black water river areas of Southeast Asia. The four varieties of Asian Arowana each originated in different freshwater areas of Malaysia, Thailand, and Indonesia. The unique physical features of these rivers, swamps and wetland areas dictate optimum tank conditions for Arowanas in captivity.
i) Temperature: Native Arowana habitats are located very close to the equator in tropical areas. Water temperature must therefore be kept at approximately 27°C (80° F). Water temperature would vary little in an Arowana’s natural environment, and they do not tolerate fluctuations in aquarium temperature, either.
ii) Black water: Arowanas natively inhabit black water rivers and wetland areas. Black water is incredibly clean and tends to support a wide variety of unique fish species specially adapted to its attributes. Black water is acidic, soft water fed by black water streams originating from ancient tropical forest soils that are low in nutrients. The lack of minerals present in these soils keeps black water soft. The decaying leaves of Ketapang Trees that fall into black water release tannins and humic acids which further soften it. These organic acids dye the water a distinctive tea color.
The brownish-yellow color of black water is believed to contribute to the bright, iridescent colors typical of many black water fish species, including Arowanas. Vibrant coloration may make it easier for species to spot each other in darkly colored water.
With this in mind, many hobbyists try to reproduce black water conditions in their Arowana aquariums. Dried Ketapang leaves are used to promote a healthy environment and lower the pH of tank water. The natural organic acids released by the leaves may help absorb undesirable chemicals, detoxify the tank, and reduce the population of undesirable bacteria.
Peat and decayed driftwood are two other black water additives used in Arowana tanks. Commercially prepared “black water extract” is another option. When creating black water conditions, care should be taken that the tank’s pH does not become too acidic or dip below 6.5 – 7.0.
i) Diet: Arowanas in the wild are predatory, surface feeding fish that hunt in shallow, shaded areas along the shore. They are notorious for leaping after food flying or hanging above the surface. Their diet consists of live food in their natural environment, and it is what they prefer to be fed in captivity.
It is not only possible, but wise to adjust your Arowana to eating some non-live foods. But for mimicking their natural environment, nothing comes closer than live foods. In the wild, Arowanas are known to feed on insects, spiders, frogs, fish, lizards, birds, bats, and even small monkeys. In captivity, farm-raised prawn, worms and feeder fish allow Arowanas to exercise their natural hunting instincts.
Their natural diet also makes it challenging to find suitable tank mates for an Arowana. In the wild, they commonly consume anything small enough to fit in their mouths. The same tends to occur in captivity.
ii) Feeding Schedule: Many experts doubt Arowanas feed every day in their natural environments. Even a large tank allows only minimal exercise for Arowanas kept in captivity. Daily feeding is therefore unnecessary and may compromise water quality.
iii) Tank Cover: Another direct result of its natural feeding habits is the Arowana’s tendency to leap from its tank. Extreme care must be taken to secure aquarium lids. Attempting to discourage jumping in any other way is unlikely to prove fruitful, and may result in harm to the fish.
Arowanas are usually found singly or in small groups in the wild. They are extremely territorial and aggressively defend the areas they occupy. Their natural instincts are at odds with housing Arowanas together.
Other surface-swimming or aggressive fish are likely to appear threatening to an Arowana. Reduce the risk of altercations by choosing one or two bottom- dwelling or larger, shy tank mates for housing with Arowanas.
Although Arowanas are typically found among shallow waters littered with reeds, wood, rocks and water plants, most hobbyists prefer to keep Arowana tanks sparsely decorated. This helps prevent injury to the fish and makes tank maintenance less tedious. Artificial plants and decorations that do not interfere with surface swimming habits are safe, low maintenance alternatives for offering some “natural” habitat features.