Order Osteoglossiformes
Family Osteoglossidae
Genus Osteoglossum
— Silver Arowana — Osteoglossum bicirrhosum [Cuvier, 1829]. Synonyms: Osteoglossum arowana, minus, vandelli. (English: Silver Arowana, Bony Tongued Fish, God Fish, Dragon Fish). Tropical South America, mainly Colombia, Guyana, western tributaries of the Amazon and Orinoco rivers. 90 cm, in aquarium 50-70 cm. They are caught as fry in Colombia and sold to aquarists worldwide.
The Silver Arowana is one of the most beautiful arowanas. It is distinguished by extraordinary flexibility, swimming like a snake, and has the ability to “bite its own tail”. It can bend its body 180 degrees. It looks especially beautiful from above when swimming and writhing – it has large, “splayed” pectoral fins of a yellowish tint.
First of all, one’s attention is drawn to the large silvery scales covering the fish’s body and the large expressive eyes. The body is covered with rigid scales in the form of bony plates. Adults have a platinum-silver coloration. Fins often range from brown to red. The long anal and dorsal fins begin at the middle of the body and extend to the tail. The anal fin is wide, with a very long base. Pectoral fins are small, light in youth, and usually darken over time.
Vision is very sharp, allowing them to see what is happening above the surface and, jumping out of the water, catch birds and other animals sitting on overhanging tree branches. Characteristic features of this species are a pair of fleshy black-blue or red-green barbels on the chin and a large bucket-shaped mouth capable of opening very wide. The lower jaw of the arowana is slightly rounded on the outside and resembles the bow of a landing craft. Therefore, the arowana can easily capture quite large prey.
The barbels at the tip of the lower jaw are large sensory devices with which it can sense and capture prey on the water surface, even in complete darkness. Males are brighter and slimmer than females. In addition, they have an elongated anal fin and a more powerful lower jaw with a noticeably protruding edge.
The unusual shape resembling a sabre blade, the delicate silvery-honey coloration of the body covered with large scales, dark fins with a red border, and interesting behavioral features make the arowana an excellent subject for aquarium keeping. The Silver Arowana practically does not change its coloration throughout its life.
Juveniles up to 20 cm in size need an aquarium with a volume of at least 130 liters, and its length should be about a meter. For fish around 40 cm in size, an aquarium of 250-300 liters (about 120 cm long) is required. You should buy fish at least 15 cm long. Since the juveniles are quite pugnacious, it is better to keep a group of at least 10 individuals – in this case, aggression is dispersed. Young fish raised together are much more tolerant of each other. With proper care and correct full feeding, arowanas reach a length of 25 centimeters or more in a year.
Most of the time, the arowana spends swimming slowly near the surface, and may periodically submerge. The arowana can also breathe air using its swim bladder. Its movements are very graceful. Aggressive predators. When choosing tank mates, it should be remembered that the arowana is a large, clearly territorial fish, meaning it does not like neighbors and tries to attack them at every opportunity to defend its territory.
Suitable tank mates can include river stingrays and active high-bodied fish of similar size. As they grow older, arowanas will increasingly fight among themselves, so sometimes they will need to be separated. It is best if the water is slightly acidic. This is a large fish that consumes a lot of food, so be sure to equip the tank with a powerful filter. A sturdy lid must always be kept closed. Large plants that are not afraid of damage, such as Vallisneria, can be planted in the aquarium.
Feed these animals bloodworms and tubifex generously in portions. They also eagerly eat pelletized artificial foods. The diet should also include small fish, tadpoles, worms, mollusks, and pieces of raw fish and beef heart. They feed mainly in the upper and middle water layers and practically do not take food from the bottom. They mature at 4 years of age. In captivity, breeding is possible only in very large containers. They live up to 12 years. pH 6.0-6.6; dH 4-12; T 24-30°C.
Identification: Silver Arowana — Osteoglossum bicirrhosum.
— Black Arowana — Osteoglossum ferreirai [Kanazawa, 1966]. (English: Black Arowana, Blue Arowana). South America, Amazon and Rio Negro river basins. 50-90 cm. It has a body shape almost identical to the silver arowana. Young black arowanas have a magnificent coloration of black and dark yellow stripes along the entire body. But this coloration, unfortunately, is lost with age.
Young arowanas up to 4 months old have a wide horizontal black stripe running from the pectoral to the caudal fin. Another wide black stripe passes through the eye. Black dorsal and anal fins. When the body length reaches 15 cm, the color gradually changes to silver or bluish-gray with red and yellow lines along the fins and tail. Then a bluish tint appears with yellow spots and a yellow fringe in the dorsal, anal, and caudal fins. Black arowanas grow slower than silver arowanas.
An aquarium for them should be as large as possible; the fish grow very quickly and, although they do not reach their maximum natural size, they easily grow up to 40 cm. A deep aquarium is not needed for arowanas; even in a tank 40 cm high, the fish descend to the bottom quite rarely, practically only when hunting for some elusive prey.
However, the length of the aquarium is most important – in any case, it should be at least 120 centimeters. Peaceful. Extremely aggressive towards their own kind. This fish is a jumper and requires a very heavy lid on the aquarium. The fish are mouthbrooders, sometimes until the yolk sacs are absorbed. pH 5.0-7.0; dH 0-12°; T 24-30°C.
Identification: Black Arowana — Osteoglossum ferreirai.
Asian arowanas, Scleropages formosus.
Description of the family Osteoglossidae. 
