Fig 1
Fig 2
Fig 3
Fig 4
Fig 5
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Order : Osteoglossiformes
Family : OSTEOGLOSSIDAE
Species : Scleropages formosus
Maximum length (including tail fin) : 90 cm
(Fishbase, 2026)
Text updated : October, 2026.
Scleropages formosus (Asian Arowana, Asian
Bonytongue, Dragonfish), is a
member of a small group of ancient fishes called bonytongues. Three other species of the genus are recognised, two of which
occur in Australia, and another which was described from Myanmar
in 2012 (Roberts, 2012). The latter, Scleropages inscriptus, is similar in form
to Scleropages formosus but its head and body is adorned with
complex markings in a maze-like pattern (Fishbase, 2026).
Their bodies are elongate, with a rounded tail fin and large dorsal,
pectoral and anal fins. The lower jaw bears two, short barbels. Their
scales are large.
There are a number of colour varieties in different regions, including
green, silver, red and golden.
Scleropages formosus naturally occurs in lakes, swamps,
slow-flowing rivers and other wetlands (Larson & Vidthayanon, 2019). They are surface
feeders; adults are carnivorous and prey on other species of fish and large insects,
while juveniles feed on small insects.
Adult males adopt the role of mouthbrooder, caring
for fertlised eggs and hatchlings in their mouths for many weeks.
This species fetches a high price as an ornamental fish, particularly
amongst Chinese communities; the international trade in arowanas has put
great pressure on native populations, which are over-harvested in many
countries.
Scleropages formosus occurs naturally in Thailand,
Cambodia, Vietnam, Peninsular Malaysia, Sumatra (including Bangka) and Borneo
(Larson & Vidthayanon, 2019). In Singapore
the species has been introduced to some reservoirs, and seems to
have successfully established local breeding populations (Ng & Tan,
2010).
Fig 1 : Yellow-tailed, silver variety, which is typically dark grey on the
back.
Figs 2 and 3 : Yellow juvenile from Singapore, found in a tributary to an
inland reservoir. The other species in Figure 3 is a
Forest Betta Betta pugnax.
Fig 4 : Example from Macritchie Reservoir, Singapore.
Fig 5 : Example from Sungei Buloh, Singapore with golden scales on its
flanks and reddish fins.
References and links :
Larson, H. and Vidthayanon, C. 2019. Scleropages formosus. The
IUCN Red List of Threatened Species 2019: e.T152320185A89797267.
Ng, H. H., & Tan, H. H. (2010). An annotated checklist of the non-native
freshwater fish species in the reservoirs of Singapore. Cosmos, 6(01),
95-116.
Roberts, T. R. (2012). Scleropages inscriptus, a new fish species
from the Tananthayi or Tenasserim River basin, Malay Peninsula of
Myanmar (Osteoglossidae: Osteoglossiformes). Aqua: International
Journal of Ichthyology 18.2 (2012): 113
Fishbase
- Scleropages formosus
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