Auckland Zoo successfully breeds rare Asian arowana

The Asian arowana, an endangered Southeast Asian fish species renowned for its beauty and spectacular jumping ability as an ambush predator has successfully been bred at Auckland Zoo.

The breeding of 16 Asian arowana fry that hatched around early December has been achieved just over a year after the Zoo’s five adults moved into the new Indonesian swamp forest habitat – an award-winning environment as part of the South East Asia Jungle Track.

“It’s incredibly exciting to be witnessing these fully independent and perfectly formed young thriving and growing bigger by the week as they continue to eagerly devour their diet of primarily shrimp, crickets, and locusts. While currently only around 7cm long and about 10 grams each, they already resemble mini versions of the five-year-old adults (60cm long and several kilos) who could eventually grow up to 90cm and a hefty 6.8kgs,” says Auckland Zoo’s ectotherms curator, Don McFarlane.

To Auckland Zoo’s knowledge, this is the first time that Asian arowana have ever been bred in New Zealand.

“For us, this early success affirms the great design of our climate-controlled swamp forest and its very sophisticated high-tech Life Support System (LSS). As well as all the science that helps inform our animal husbandry and care, science is at the core of creating and maintaining our LSS to achieve the right water chemistry, quality, and temperature to support these arowana and all the species in this habitat,” explains Don.

Asian arowana courtship behaviours involve the male and female circling one another and engaging in gentle body-rubbing. Once the female deposits her eggs on the habitat floor, the male fertilises them before scooping them up in his mouth, where they remain until after they hatch and the fry have fully absorbed their yolk sacs - which can take a number of weeks.

As this species is aggressive and the fry would be at risk from the adults in the main aquarium habitat, towards the end of the incubation period the Ectotherm team moved ‘dad’ into a separate tank in the swamp forest’s aquarium support facility – specially designed for this type of breeding and rearing. (The 14 surviving young are also now separated off into several different tanks according to their size to manage competition for food and to help ensure all individuals have optimal opportunities to thrive).

“Asian arowana are mouth brooders and it’s the male who does all the work following egg fertilisation. It’s a big sacrifice as during the eight-week incubation period while carrying his brood safely within his large oblong-shaped mouth he’s unable to feed, so loses condition. In the wild this makes him very vulnerable so he must seek out shelter and seclusion,” says Don.

Increasingly at risk in the wild from ongoing loss of its freshwater habitats (slow-moving waters, blackwater rivers, forested swamps, and wetlands) and the illegal pet trade, the Asian arowana is classified as ‘Endangered’ on the IUCN (International Union for Conservation of Nature) Red List.

“Physically and behaviourally, the Asian Arowana is an impressive and powerful species that as an apex predator plays a really important role in the ecosystems it inhabits and needs protecting.”

“There is so much to admire about it! Despite its considerable weight, it can still jump well over a metre out of the water to gracefully pluck off prey items like invertebrates and vertebrate species like frogs. Physically its iridescent scales have this impressive pre-historic look about them and its head and mouth are beautifully bizarre. Often likened to the Chinese (mythical) dragon, it has two barbels (sensory organs that assist it to locate fish in murky waters) sticking out the front of its strange shovel-like face and beautiful dragon-like pectoral fins that look like wings.”   

Asian Arowana Fast Facts

• The Asian arowana (Scleropages Formosus), also commonly known as the dragonfish, is a freshwater carnivorous fish and apex fish predator native to Southeast Asia (including countries such as Indonesia, Malaysia, and Thailand). It inhabits slow-moving waters, blackwater rivers, forested swamps, and wetlands habitats. Can grow up to 90cm (almost a metre) and with up to almost 7kg!
• Conservation status: Listed as ‘Endangered’ (International Union for Conservation of Nature/IUCN Red List) and decreasing in population.
• Key threats: Loss and damage of its the freshwater ecosystems it inhabits (slow-moving waters, blackwater rivers, forested swamps, and wetlands) and the illegal pet trade.
• Diet: In the wild, this carnivorous hunter of lowland swamps and rivers dines mostly on smaller fish and invertebrates, but occasionally amphibians and even small birds and reptiles. In the zoo environment, this species eats live vertebrates such as crickets and locusts and is given shrimp and supplementary pellets.
• Breeding: Known as mouth brooders, this species cares for its eggs and young in its mouth. After courtship and spawning, the male scoops the fertilised eggs into his large oblong-shaped mouth and keeps them safe throughout the incubation period (approx. 8 weeks) and even up to one to two mouths afterwards as tiny vulnerable fry.
• Asian arowana at Auckland Zoo: The Zoo’s Indonesian swamp forest habitat within the South East Asia Jungle Track is home to five five-year-old adult Asian arowana. Visitors can see these majestic adults, but the offspring produced from this latest breeding, live in separate fish rearing tanks in the aquarium support facility.