Asian Arowanas

Order Osteoglossiformes

Family Osteoglossidae

The name Asian Arowana combines several varieties of freshwater fish of the genus Scleropages. Some sources distinguish these variations into separate species, while others consider the breeds as a single species Scleropages formosus.

In the wild, Asian Arowanas inhabit slow-flowing rivers heavily lined with vegetation along the banks. Asian Arowanas have adapted to freshwater and cannot survive in the ocean. Adults feed on small fish, while fry consume insects. The morphological similarity of all Scleropages species demonstrates their minimal evolutionary adjustments compared to their ancestors.

Traditionally, two variations of arowanas inhabit Malaysia: golden and green. Green individuals are the most common, and their cost is lower. The Golden Arowana variation (crossback) is found in the Krian River and the Perak tributary. The water in fast-flowing river basins has a slightly acidic reaction and is free from surrounding organic pollution, particularly in shallow areas where vegetation overhangs the banks.

Several color variations of the Asian Arowana are found in their natural habitat. These include:

1. The most common Green variation, found in Indonesia (Kalimantan and Sumatra), Vietnam, Myanmar, Thailand, Cambodia, and Malaysia.

2. The Silver arowana (not to be confused with the species Osteoglossum bicirrhosum), which is considered by some to be a branch of the green variation. It, in turn, has two varieties: the silver grey-tailed (or Pinoch arowana) and the silver yellow-tailed. The variation is found on the island of Borneo in Indonesia.

3. The Red-tailed golden arowana is found in northern Sumatra, Indonesia.

4. The Golden arowana (crossback), Malaysian blue, or Bukit Merah blue is found in Pahang state and the Bukit Merah area in Perak state, Peninsular Malaysia.

5. The Red, super red, blood-red, or chili red variety is known in the upper Kapuas River and adjacent lakes of western Borneo, Indonesia.

In 2003, a study was published that divided S. formosus into 4 independent species. This classification, based on morphology and genetics, includes:

1. The name Scleropages formosus was given to the Green Arowana variety. The Golden Arowana (crossback), which was not considered in the study, is also assigned to this species and is closely related to Scleropages aureus.

2. The Silver Asian Arowana was described as Scleropages macrocephalus.

3. Scleropages aureus – Red-Tailed Golden Arowana.

4. Scleropages legendrei – Super Red Arowana.

Asian Arowanas reach lengths of over 90 cm. All members of the genus Scleropages have a long body; large, elongated fins; dorsal and caudal fins located far back on the body; and a larger caudal fin compared to their South American relative Osteoglossum bicirrhosum. The mouth is oblique with a very wide gape. A pair of barbels is located at the tip of the protruding lower jaw. Gill rakers are robust. The teeth of Asian arowanas are located on multiple bones, including the jaws, vomer, palatine, parasphenoid, pterygoid, and tongue.

The scales are large and cycloid, and in some varieties, they have a metallic coloration with a distinct mosaic pattern of ascending edges. Lateral scales are arranged in horizontal rows from the most ventral to the most dorsal (fifth level), with dorsal scales gathered into a sixth level.

They reach sexual maturity slowly and are difficult to spawn. In captivity, successful breeding is usually observed in large ponds rather than aquariums. Fry show no sexual dimorphism. It begins to manifest only by the 3rd-4th year of life at a body length of 45-60 cm. Sex determination is based on body shape and mouth cavity size. The male has a slender, low body, a larger head and mouth, and more intense coloration compared to the female. A large mouth with a strongly lowered lower jaw allows the male to successfully incubate eggs. A more aggressive temperament and strong competition for food are normal for males.

Asian arowanas are mouthbrooders. The female releases a batch of orange-red eggs. The eggs have a diameter of 8-10 mm, are rich in yolk, and mature within 1 week. The male fertilizes them and takes them into his mouth. He does not feed and appears more peaceful compared to other individuals. In addition, the lower part of his mouth cavity sags. After hatching, the larvae continue to live in the male’s mouth for the next 7-8 weeks until the yolk is completely absorbed. Only upon reaching a length of 45-50 mm are the fry released.

Captive-bred arowanas can be legally sold in two ways. The first is by providing the individuals with a certificate of authenticity and birth certificate. The second involves implanting special microchips into the fish as an identifier for each individual.

Judges evaluating the dragon fish are extremely meticulous. Coloration and body shape account for only 30% of the total score when evaluating each specimen, while 40% are attributed to the characteristics of the tail, fins, and mouth. The fish’s eyes should look upward, barbels should stretch parallel to each other, and fins should be intact with well-defined edges. Individuals whose scale rows cross the back instead of splitting into two rows along the sides of the gills are called “dragon in the dark”, and their price is doubled. Such pricing is a mecca for fraudsters who feed less attractive arowanas with grasshoppers stuffed with hormones, thereby significantly enhancing the fish’s coloration. They are divided into classes: A; AA; AAA; AAA+.

Asian arowanas differ from their Australian relatives S. jardinii and S. leichardti by having fewer (21-26) lateral scale lines (versus 32-36 in Australian species), elongated pectoral and pelvic fins, and a more elongated snout.

Green arowanas have a dark green back, silvery- or golden-green sides, silvery or whitish undersides, and dark greenish or bluish sheens running along the lateral scales. In adults, the top of the eyes and the head behind the eyes are light emerald.

Grey-tailed and yellow-tailed silver arowanas have a dark green back, silvery or whitish belly, and silvery sides with dark ring patterns on the lateral scales. In the yellow-tailed variety, the fin membrane is yellow with dark grey rows. In grey-tailed individuals, the fins are uniformly dark grey.

Mature red-tailed golden arowanas have scales, gill covers, and pectoral and pelvic fin membranes of a golden color with a diamond metallic iridescence, while the back is dark. In juveniles, the area before the appearance of golden metallic coloration has a metallic silver color. The coloration of the anal fin and the lower part of the caudal fin ranges from light brown to dark red.

Adult “Crossback” golden arowanas differ from the red-tailed golden variety by having golden coloration running across the entire back. In addition, this variation lacks the red fin coloration seen in the red-tailed arowana.

In sexually mature super red arowanas, the gill covers, lateral scales, and fin membranes are metallic red, varying from reddish with a golden sheen to deep red.

    Identification: Arowana Formosa — Scleropages formosus.

There are three color types of Asian arowanas: green, golden, and red.

— Golden Arowanas have two forms. “Red Tail Golden” (RTG), also known as the red-tailed golden or Indonesian golden. It possesses a wide color palette, including blue, green, or gold colors, with golden rims on the outer edge. The golden rim reaches only the 4th row; the remaining scales extending to the back are dark and do not iridesce. This is the most affordable of the “colored” arowanas. Noticeably higher, sometimes on par with reds, is “Cross Back Golden” valued by enthusiasts—meaning cross-backed or Malaysian golden arowanas, represented by several varieties depending on the main scale color: “Blue Base” – blue base under golden coloration, blue scales with iridescent shimmer; “Golden Base” – golden scale on a golden base, has a beautiful golden color that looks like a gold ingot; “Purple Base” – purple base under golden coloration; “Green Base” – green base; “Silver Base” – silver base; “Electric Blue” has a deep visible blue sheen with a golden rim along the outer edge of the entire body. In these arowanas, the golden rim on the scales is thinner. From a distance, the fish often appears blue. “Golden Head” – golden-headed. Grade 2 (Banjar Red) – Young fish have red fins and a body with a greenish tint. They are very similar to young red arowanas, however, an adult specimen is easy to distinguish. The body becomes grey-green, the fins light red, and at an older age, yellow.

“Pahang Gold”, “Malayan Bonytongue”, “Bukit Merah Blue”, “Taiping Golden”, and “Malaysian Gold” are simply different names for the same fish “Cross Back Golden” from different corners of Malaysia, Perak and Terengganu provinces, Bukit Merah Lake, and Johor. “Super Grade Red Splendour” is the result of crossing Golden and Red arowanas. Due to its hybrid origin, it turned out to be a rather exotic variant, exhibiting the color characteristics of both species. It features even brighter coloration, better scales, and a luxurious body. “Premium High Gold” appeared through natural crossing of the species from Bukit Merah Lake in Perak, Malaysia. This is the most pronounced and beautiful golden color variant of the Asian arowana. At a young age, the golden rims reach only the 4th row of scales, but later they spread up to the 6th row and color the entire back. The body color of the adult arowana is lighter than the fin color. Thus, an adult arowana will look like a swimming gold ingot.

— Green Arowanas “Green Arowana”. This is the most common and cheapest Asian variant. Most of these arowanas have a greyish-green color with a dark purple tint in the center of the fish’s body and a dark grey-green striped tail. It has a large, rounded head and a large mouth compared to other species. — “Yellow Tail Arowana” – Considered a hybrid between a golden and a green arowana. Its scales are generally milky white with yellow fins and tail.

— Red Arowanas are valued above all others; their scales and caudal fin are red. There are also ruby-colored and chili-colored arowanas. They are subdivided by quality. They are either — “Super Red” – top-category red arowanas, which are subdivided into “Blood Red”, “Chilli Red”, “Orange Red”, “Golden Red”, and “Violet Fusion”. “Chilli Red” is larger, has a more pronounced red color, red eyes, and a tail with diamond spots, whereas “Blood Red” is thinner and longer, the scales are not as red, the eyes are smaller, and the tail is wider. These differences are evident already in young arowanas.

“Orange Red” – upon reaching sexual maturity, the fish are not fully colored in red, but orange colors predominate, with red appearing only on the tail. “Golden Red” – the body is colored golden-yellow, and the barbels are sometimes red. Instead of red, they have more pink color. “Violet Fusion” – they have a prevailing violet tint in the base of the color palette and feature the most beautiful body shape. Their tail is generally larger and pectoral fins are big. It colors up intensively at an early age, which distinguishes it from other Red Arowanas. — “Second Grade” red arowanas of the second category, these individuals are also designated as Red Arowana (2) or Red Arowana (B).

The first class has a color that starts from yellow to orange, blood red, and chili. Young 1st-class arowanas have a tail and caudal fin of very intense color, with shiny golden scales featuring a small green border at the base. The more intense the color, the more expensive they are. With age, the scales and gills turn red. Young 2nd-class arowanas have orange fins, scales without a defined color, and are often whitish-silver. With age, they will have only pink or orange fins, and the scales and gills will turn pink or orange. For the red color to manifest in all its glory, peat extracts are added to soft water with a pH of about 6, or natural peat is used. In dark amber-colored water, especially under dim lighting, red arowanas look stunning. By the way, a fish belonging to the “Second Grade” category does not always mean that this specimen has poor coloration. Simply for various reasons, the breeder does not recommend using such specimens for selective breeding.

Genus Scleropages, Scleropages formosus.

Osteoglossum bicirrhosum, Osteoglossum ferreirai, Silver and Black Arowana.