Ultimate Arowana species profile and distinction

Ultimate Arowana species profile and distinction

In order to understand and appreciate a particular species in any real depth, it is essential to know something about its closest relatives. Thus, similarities and differences can be put into perspective, and a deeper insight gained into the unique qualities of the species concerned. It is with this in mind that the following species profiles have been compiled.

Silver Arowana

Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli

(1) – Scientific Name

Osteoglossum bicirrhosum, Vandelli

(2) – Synonyms

Ischnosoma bicirrhosum, Osteoglossum vandelli

(3) – Distribution

Amazon drainage, western Orinoco, Guyana

(4) – Habitat Preferences

Flooded forest and lakes; often found in shallow near the shore, where they make relatively easy targets for fishermen.

(5) – Preferred Water Conditions

Slightly or moderately acid, soft water maintained at between 24-30°C (75-86°F). While deviations from these chemical conditions can be tolerated in aquaria, any changes must be gradual, and ammonia and nitrite levels must be kept to a minimum.

(6) – Size

Maximum length recorded in the wild is 100cm (39in), but the vast majority of both wild-caught and aquarium specimens are usually smaller.

Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-1 Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-2 Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-3

(7) – Diet

In the wild, Michael Goulding and colleagues (1980) carried out gut content analyses of samples collected in the Rio Machado which revealed a broad range of prey items. The highest percentage (over 40%) consisted of insects and spiders, but remains of crustaceans, molluscs, fish (just over 10%), snakes and even birds were also found. Some plant material was also recorded, but this was thought to have been incidental and to have been ingested accidentally along with animal prey. An earlier author (Lowe- McConnell, 1964) also reported bat remains.

In aquaria, this species will accept insects and other substantial live and frozen foods, as well as meat-based home prepared formulae such as boiled fish paste and fish chunks. Pellets may also be taken. Young specimens must not be fed until they absorb their yolk sacs.

Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-4

(8) – Breeding

The sexes are very similar to each other, with the female being somewhat deeper-bodied than the male. Like all its relatives, O. bicirrhosum is a mouthbrooder. In the wild, spawning occurs at the onset of the annual rains (around December and January in the Rio Machado). Goulding (1980) recorded 210 ova in a ripe female. Fertilized and developing embryos are incubated orally by males for 40-60 days. When the fry is released, they can measure up to 10cm (4in) in length.

The beginning of the rainy season varies throughout the natural range of the species but is invariable during the autumn and winter months, so wild-caught young Silver Arowanas become available during this time, many still carrying substantial yolk sacs. Provided these young fish are acclimatized properly and handled carefully, they settle down well and grow very quickly. A size of 30cm (12in) can be attained in as little as six months on a diet of meat-based live and frozen foods.

There are few accounts of successful aquarium spawnings, but the commercial of this species is becoming established in some countries. The result of these ventures is that the Silver Arowana is now available throughout most of the year.

Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-6 Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-5

(9) – Additional Details

The Silver Arowana is considered an important food fish in the Amazon where it is often hunted with harpoons or bows and arrows at night. The species natural inclination to swim in shallow water near to the shore makes it an easy target, with large specimens being caught in as little as 30cm (12in) or less of water. Despite the ease with which they can be hunted, wild stocks of the Silver Arowana are not under threat, since the species is both abundant and widely distributed in Amazonian waters.

Just as the has a special place in Far East folklore, so does the Silver Arowana among the Amazonian river people. It is, for instance, one of the few fish that women who have recently given birth are allowed to eat during their recovery period.

Like the Dragon Fish, the Silver Arowana is an excellent jumper, often attacking flying or terrestrial prey perched on branches above the water . This acrobatic ability has earned it the name of water monkey (macaco d’agua) in parts of the Brazilian Amazon.

Black Arowana

Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-8

(1) – Scientific Name

Osteoglossum ferreirai, Kanazawa

(2) – Synonyms

None

(3) – Distribution

the Rio Negro

(4) – Habitat Preferences

As for O. bicirrhosum

(5) – Preferred Water Conditions

Similar to those preferred by O. bicirrhosum. However, because of the acidic conditions which exist in the Rio Negro, this aspect of the water chemistry may be somewhat more important for the long-term well-being of O. ferreirai.

(6) – Size

Sizes above 60cm (24in) have been recorded in wild-caught specimens.

Species-Profiles-Black-Arowana-Scientific-Name-Osteoglossum-ferreirai-Kanazawa-1 Species-Profiles-Black-Arowana-Scientific-Name-Osteoglossum-ferreirai-Kanazawa-2 Species-Profiles-Silver-Arowana-Scientific-Name-Osteoglossum-bicirrhosum-Vandelli-3 Species-Profiles-Black-Arowana-Scientific-Name-Osteoglossum-ferreirai-Kanazawa-4

(7) – Diet

Gut content analyses of wild caught specimens carried out by Goulding et al. (1988) show a similar range of food items to those consumed by O. bicirrhosum.

(8) -Breeding

As O. bicirrhosum. Young Black Arowanas are particularly attractive, having a predominantly black body with a contrasting creamy yellow stripe that runs from the snout through the top edge of the eye and along the upper part of the body, ending at the tip of the caudal (tail) fin. There is also a pronounced vertical creamy yellow band just behind the head.

(9) – Additional Information

The Black Arowana, while being overall very similar to its Silver relative, is somewhat slimmer in appearance owing to its higher number of lateral line scales, dorsal and anal fin rays and vertebrae.

Gulf Saratoga (pearl ,Northern Spotted Barramundi)

Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-6

(1) – Scientific Name

Scleropages jardinii, (Saville-Kent)

(2) – Synonyms

Scleropages jardini

(3) – Distribution

Northern Australia from the Jardine River to the Adelaide River, and central/southern drainage systems of Papua New Guinea and Irian Jaya.

(4) – Habitat Preferences

According to Merrick and Schmida (1984), this species, is found in a wide range of habitats, including faster-flowing stretches in the upper reaches of watercourses and still waters (billabongs), exhibiting a preference for clear water conditions. According to Allen (1989), the Gulf Saratoga prefers still waters and slow-moving stretches.

Although it can swim at all levels, the Gulf Saratoga is more commonly found in the middle and upper zones of the water column, often being spotted near the surface or close to the shoreline and among submerged vegetation.

(5) – Preferred Water Conditions

A wide range of temperatures is reported to be tolerated, with 18-33°C (c. 64-91°F) for general maintenance. Spawning is said to occur in the early summer season when temperatures rise above 23°C (c. 73°F).

(6) – Size

Merrick and Schmida (1984) report a record size of 90cm (35.4in) and a weight of 17.2kg (37.91b). Most specimens are, however, considerably smaller, between 50-60cm (c. 20-24in) in length.Allen (1989) reports that S.jardinii may attain 27kg (59.51b) in weight. Fully mature males may be a little longer than mature females.

(7) – Diet

In the wild, fish, Crustacea, insects and other vertebrates and invertebrates form part of the natural diet. In aquaria, this species can be weaned on to fresh and frozen meat-based foods.
Young Gulf Saratogas are said to begin feeding at a length of 2-3cm (0.8-1.2in) even before the yolk sac is fully absorbed.

Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent) Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-2 Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-3 Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-4 Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-5

(8) – Breeding

Telling the sexes apart is impossible during the developmental stages. Even in fully mature specimens, sexual dimorphism is not externally apparent, although certified males of around five years of age have been shown to attain a slightly greater length than females (see Size above).

Like the other members of the subfamily, S. jardinii is a mouthbrooder. However, Allen reports the mouthbrooding parent to be the female. In the Osteoglossum species and the Dragon Fish, S. formosus, it is the male that undertakes this role.

There are no reports of successful aquarium breeding attempts. Legget and Merrick (1987) recommend the use of earthen (mud) pounds for this purpose. Water conditions should be a temperature of around 23°C (c. 73°F), pH between 6.5 and 8.0 and total hardness between 0-100 ppm (mg/1).

In the wild, spawning occurs just before or during the early stages of the rainy season (November or December), which is early summer in the southern hemisphere.

The females, like their counterparts in the other members of the subfamily, possess a single ovary. Numbers of eggs range from around 60-95 according to Merrick and Schmida and 30-130 according to Allen. These figures are higher than the average range for the Dragon Fish but lower than those recorded for the Silver Arowana. At 10-11mm (c. 0.4in) the eggs are large and rich in yolk, a vital ingredient for the developing embryos.

Hatching takes 1-2 weeks, but the newly-hatched fry is incubated orally for further 4-5 weeks, during which time the yolk sac is gradually absorbed. , however, begins before total absorption has been completed. On a good, meat-based diet, juveniles can attain a standard length (SL), measured from the snout to the base of the tail, of around 10cm (4in) in as little as three months.

Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-5 Gulf-Saratoga-Scientific-Name-Scleropages-jardinii-(Saville-Kent)-1

(9) – Additional Information

Like its closest relative, the Spotted Saratoga (S.leichardti), the Gulf Saratoga is deemed a good sports fish by anglers in its native Australia owing to its excellent fighting qualities. It is also said to make delicious eating.

Some adult specimens kept too large aquaria have been observed gulping air at the surface and releasing bubbles shortly afterward. Since the water was of good quality and well aerated, it is believed this behavior indicates the possession of an auxiliary breathing organ or mechanism, probably the swim bladder as in other Bonytongues.

Spotted Saratoga (Spotted Arowana,Spotted Barramundi)

d-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther
Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther

(1) – Scientific Name

Scleropages leichardti, Gunther 1864

(2) – Synonyms

None

(3) – Distribution

The Spotted Saratoga, has a much more restricted distribution than the Gulf Saratoga, being found naturally only in the Fitzroy River system of central-eastern Queensland. Stocks have been transferred from here to south-eastern Queensland, including the Mary River system. Allen (1989) reports that Gunther’s published Burdekin River location for this species is incorrect.

(4) – Habitat Preferences

Although its distribution is patchy, S. leichardti is more commonly encountered in turbid water in the upper reaches of streams and rivers and is not usually found near estuaries. During the daylight hours of the warmer months of the year, Spotted Saratogas tend to swim just under the surface and close to vegetation, migrating to deeper water once surface temperatures rise above approximately 30°C (86°F).

(5) – Preferred Water Conditions

Still or slow-moving water maintained between 15-30°C (59-86°F) is recommended, although the full temperature range tolerated by the species is 7 40°C (c. 45-104°F). See also Breeding below.

(6) – Size

Sizes up to 90cm (35.4in), and weights of 4kg (8.81b) are reported, but lengths of 50-60cm (c. 20-24in) are more common. As the lighter weight indicates, when compared to a similarly-sized S. jardinii, S. leichardti is, overall, a slightly slimmer fish. Allen quotes the greatest body depth as being 23-25% of the Standard Length for S. leichardti and 25-28% for S. jardinii.

(7) – Diet

Insects, both aquatic and terrestrial, account for the largest percentage of the natural diet of adults, but aquatic vertebrates such as fish and frogs are also taken. Saratogas will jump out of the water in their attempts to catch flying insects. In captivity, a meat-based diet, including fish chunks, prawns, and even mice, has proved acceptable, but this species is regarded as a fussy feeder.

Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther-4 Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther-3 Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther-2 Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther-1

(8) – Breeding

Sexing is as difficult of this species as in S. jardinii. Courtship begins around September/October, and spawning is said to occur during the spring when temperatures are between 20-23°C (68-73°F). Actual spawning takes place near the surface at night and away from the shore. The 50 or so large eggs, measuring around 10mm (0.4in) are incubated orally by the female (Leggett and Merrick). Hatching occurs between 1-2 weeks following fertilization, with the total incubation period lasting 5-6 weeks. A size of 10cm (4in) can be attained by juveniles in about three months on a good diet.

No reports of successful aquarium spawnings are available, but Leggett and Merrick recommend the following environmental parameters for earthen pond spawning attempts: the temperature at 20-23°C (68-73°F); pH between 7 and 9; total hardness 5-150 ppm (mg/1).

(9) – Additional Information

In addition to being somewhat slimmer (see above), the Spotted Saratoga (S. leichardti) can be distinguished from the Gulf Saratoga (S. jardinii) in having fewer dorsal fin rays (15-19 instead of 20-24) and anal fin rays (25-27 instead of 28-32). It also has a proportionately smaller head, accounting for 21-26% of the Standard Length, rather than 28-31%. The angle of the mouth is also somewhat shallower; about 24-25° about the body’s horizontal axis, rather than 41-45°. One of the most easily distinguishable characteristics, though, is that in mature S. leichardti, the forehead profile leading on to the back of the fish is almost straight, while in S. jardinii, it is distinctly convex. This refers to mature specimens in regular swimming positions and not, as in photographs of some preserved/anesthetized specimens, laid out on their sides.

In S.leichardti the belly region is white, while in S.jardinii, it is bronze in color. There are also one or two orange or red spots per scale in S. leichardti and three to four orange or red ones on the scales of S. jardinii, giving these a crescent-like pattern.

Merrick and Schmida (1983 a, b) report that occasionally generous red individuals of S. leichardti are recorded. Interestingly, red specimens of the Dragon Fish (S. formosus) are also found in the wild.

Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther-9 Spotted-Saratoga-Scientific-Name-Scleropages-leichardti-Gunther-8

5.Dragon Fish(Arowana Asian)

(1) – Scientific Name

Scleropages formosus, (Muller and Schlegel)

(2) – Synonyms

None

(3) – Distribution

Natural wild populations are known to exist in Cambodia, Lao PDR, Peninsular Malaysia, the Philippines, Vietnam and Indonesia (Kalimantan and Sumatra).The best wild red specimens are found in West Kalimantan. There is some doubt regarding the existence of wild populations in Myanmar (formerly Burma), and the species may now be extinct in Thailand. Populations are also known from various locations in Singapore, most or all arising from releases, including that of surplus captive-bred specimens from an official Government breeding program carried out during the early 1980s.

(4) -Habitat Preferences

Still or slow-flowing waters which are often turbid or weedy. The Dragon Fish is said not to occur either in mountainous regions or lowlands in nature. This species shows a distinct preference for the upper layers of the water column, particularly at night and during courtship.

(5) – Preferred Water Conditions

Although found in turbid waters in the wild – a condition faithfully reproduced in the earthen ponds in which this species is bred in captivity- Dragon Fish appear to do equally well in bright, good-quality water to great aquaria.

arowana-asian-dragon-fish-whatfishthinks
Broad-bodied specimen.

(6) – Size

Up to around 90cm (35.4in) has been reported, but usually, the fish is smaller. In the Primary Production Department (Singapore) collection, the maximum length attained by an individual specimen was 70.5cm (27.8in); its weight was 4.2kg (9.31b). Some of the specimens in this collection are more than 12 years old.

(7) – Diet

In the wild, the Dragon Fish will eat a broad range of invertebrate and vertebrate foods, largely from the surface and the upper layers of the water column. Like its relatives, though, it will also jump out of the water to grab flying prey or small animals resting on branches and other perches above the water.

In captivity, a wide range of meat-based diets is accepted.
Breeding Lim et al. (1996) report that Dragon Fish become mature during the third to fourth years of their lives and usually begin to spawn from the fourth year. At this time, they measure between 45-60cm (18-24in). Dragon Fish generate almost throughout the year, with peak spawning occurring between July and December.

The sexes are indistinguishable before maturity and are only identified with considerable difficulty (and experience) even after maturity is reached. Males may be slightly slimmer than females, and the skin of their chin area may show signs that they possess a distendable buccal cavity in which to incubate the eggs. Males may also maintain bigger mouths.

Actual spawning is preceded by a protracted period of courtship and pair bonding which takes place over a period of two to three months. Most courtship sequences are observed at night when the fish tend to swim closest to the water surface. They do, however, also occur during the day, both in open water and close to the shore. Side-by-side body quivering/flexing and prolonged nose-to-tail circling are standard features of these bouts of courtship behavior, during which the courting pair will vigorously chase away intruders.

Female Dragon Fish possess a single ovary which, when ripe, contains around 20-30 large oval approximately 1.9cm (0.75in) in diameter, according to Scott and Fuller (1976). However, later studies, plus personal observation, have shown that fecundity can be considerably higher. In August 1988, for example, a brood of fry harvested from the mouth of a Green Dragon male (mistakenly identified as a female) numbered no fewer than 93 individuals (Dawes, 1989), but this is exceptional. Lim et al. report that, more commonly, the brood size ranges between 4 to 62 for Red Dragons, with an average number of 34.9 based on 102 families.

arowana-asian-dragon-fish-whatfishthinks-com-1
A handful of larval fish
, freshly collected from a brooding male
arowana-asian-dragon-fish-whatfishthinks-com-2
Red x Golden Dragon Fj hybrid.

The male incubates the yolk-rich eggs and, subsequently, the larvae in his mouth for approximately 5-6 weeks, during which period a very clear chain pouch is detectable. The male appears not to feed during incubation and is more placid than at other times.

The large yolk sacs take several weeks to be fully absorbed, by which time the fry have attained a Total Length (TL) from tip of snout to tip of the tail of around 9cm (3.5in). Teo (1993) reports that it takes almost two months for larvae measuring 2.6cm (c. lin) TL and possessing a yolk sac of 1.6cm (0.63in) diameter to attain a length of 9cm (c. 3.5in). However, feeding does commence before the yolk sac has been fully absorbed.

The growth of juveniles is uneven and, owing to the aggressive nature of the species, physical injury or even cannibalism can occur unless preventive measures are undertaken, such as isolating individual specimens.

Despite this inherent threat to health, Teo reports that the survival rate of fry during their first six months is as high as 83%. At six months, a length of 26.8cm (10.6in) and a weight of 162.8g (5.7oz) will have been reached in pond-raised fish (see below for comparison with aquarium raised specimens).

(8) – Breeding

Dragon Fish in aquaria was first achieved in 1972 by HiroshiAzuma in Japan. However, it took a further 30 or so spawnings over a period of 17 years to achieve success in a male retaining eggs until theyhatched. The successful event occurred after a spawning between a 9-yearold male and a 7-year-old female, the pair s pre-spawning courtshipactivities lasting 2-3 months.

arowana-asian-dragon-fish-whatfishthinks-com-3
Dragon Fish in shallow water.

When the fish eventually spawned, they did so near the bottom of abare-based aquarium. The eggs were released in clusters, fertilised by themale and scooped up by him into his mouth. For a period of 22 days,untilthe female was removed, the pair swam together all the time.

Hatching is assumed to have occurred 12 days after spawning asevidenced by the discovery of an empty eggshell (membrane) on thebottom of the aquarium. The fry were retained in the male’s mouth for afurther 37 days, at which point they were allowed out for short periods. Ittook another 12 days before they finally swam free of their father forextended periods’.

During this incubation/protection phase, the maleexhibited dark oval mandibular patches, one on each side of his lower jaw.These were referred to by Azuma as ‘brooding marks’ and their purposemay have been to act as orientation marks for the fry to re-enter theirfather’s mouth after their external forays, as happens in mouthbroodingcichlids.

Although by this time the yolk sacs were small, it took five further daysbefore the fry began to accept livefood (bloodworms). Even at this young age, the fry were aggressive towards each other and therefore had to beseparated in small individual aquaria. Sizes of around 7.5cm (3in) wereattained within 60 days of spawning, around 14.2cm (5.6in) at 120 days,18.3cm (7.2in) at 180 days, and a maximum of some 22.9cm (9in) at 210days. No indication is provided as to whether these figures refer toStandard Length or Total Length.

arowana-asian-dragon-fish-whatfishthinks-com-4
Red Dragon spawners being released into a pond

A comprehensive report of his whole 20-year project is provided byHiroshi Azuma in the January 1992 issue of the American hobby magazineTropical Fish Hobbyist . This fascinating article should be regarded asessential reading by anyone attempting to breed Dragon Fish in aquaria.

Caution must, however, be exercised in extrapolating directly fromthis, albeit extremely valuable, aquarium-based account to conditions andbehaviour in the wild or in earthen ponds. In the aquaria used by Azuma,for example, there was no gravel on the bottom. Therefore, even if the pairwere genetically disposed towards producing a spawning depression, theywould have been unable to do so. Further, while the female was observedto swim close to the male for several weeks after spawning, brooding malesare often seen swimming on their own in earthen ponds.

Clearly, much more needs to be learned and discovered about thecourtship and breeding of the Dragon Fish but, thanks to methodicalobservers and expert practitioners such as Hiroshi Azuma, valuableheadway is being made all the time.

(9) – Additional Information

Scleropages formosus occurs naturally in three primary color forms. In Malaysia, most specimens are either Green or Golden Dragon Fish, while in Indonesia most are Gold or Red (Teo, 1993). There is also considerable variation within each color variety. The Sumatran Red Dragons, for example, carry a distinct, dark (almost black) broadband down the top of the back. White Dragons are reported by Luxmore (1990) from southern Sumatra and green, white and black varieties from the coastal districts of Indonesia.

arowana-asian-dragon-fish-whatfishthinks-com-5
Releasing a Red Dragon male back into the pond after harvesting of fry.

At least one breeder in Singapore (Lee Ah See) has cross-bred Golden and Red Dragons. The resultant fish are, in my opinion, not as attractive as the pure varieties.

Occasionally, albino specimens have been recorded. One such individual was featured by W J Tavip (1995) in an article in Tropical Fish Hobbyist (see Bibliography).

(Image) http://www.arofanatics.com/forums/showthread.php?t=355155

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