Rating Availability Hardiness Overall appeal

Species description

• Physical description....
  • The Silver Arowana is a large, elongated and laterally compressed fish.
  • The long anal fin extends from the midsection just behind the pelvic fins.
  • The dorsal fin starts in the last third of the body. The dorsal and anal fins almost look fused to the caudal fin.
  • The caudal fin is quite small and rounded in shape.
  • The pectoral and pelvic fins are slender and the pectoral fins are quite long.
  • These fins are silver in colour in juveniles, darkening as the fish gets older.
  • The mouth is large and trap-like. It faces upwards and has two barbels located on the lower jaw.
  • The barbels range in colour from black to blue to green to red.
  • The mouth contains numerous small, sharp teeth. [Ed. Note: Be careful feeding them by hand - if they jump and latch onto your fingers they leave a painful cut - this was learnt from personal experience]!
  • The body colour, while predominantly silver may contain iridescences of red, pink, gold and grey/black, depending on the sex, age, and habitat of the individual fish. Usually the Arowana is white with a silvery iridescence, but is often pink with a rainbow iridescence.
  • The eyes are large and dark and located near the top of the head.
  • The body is covered with large scales and the head is covered with bony plates.
• Taxonomy....
  • Kingdom: Animalia
    • Phylum: Chordata: Sub-phylum: Vertebrates - Group: Fish
      • Class: Osteichthyes (Bony Fish): Sub-class: Actinopterygii (Ray-finned Fish)
        • Order: Osteoglossiformes (Bony Tongued Fish)
          
        • Family: Osteoglossidae
          • Genus: Osteoglossum
        • Species: bicirrhosum
• Geographical variants....
  • None, although colouring can vary between individuals.
• Similar species....
  • The Silver Arowana may be commonly confused with Scleropages formosus (Asian Arowana) and Scleropages leichardtii (Saratoga).
  • Differences between Osteoglossum bicirrhosum and Scleropages formosus.
  • The Silver Arowana is a more slender fish than the Asian Arowana, which has quite a stocky appearance in comparison.
  • The anal fin on the Silver Arowana are much longer and the dorsal fin is not as high or rounded.
  • The pelvic fins on the Silver Arowana are much longer than those of the Asian Arowana.
  • Images:
    • Silver Arowana (below left); Asian Arowana (below right)
      
      
  • Differences between Osteoglossum bicirrhosum and Scleropages leichardtii
  • Scleropages leichardtii is easily distinguished from the Silver Arowana by the more rounded head profile and the shorter-based anal fin.
  • The pelvic and pectoral fins are much longer in the Silver Arowana and the caudal fin is more rounded where the caudal fin of the Saratoga is more fan-shaped.
  • In the Silver Arowana, the anal fin starts almost right behind the pelvic fins, while in the Saratoga it starts much further back towards the rear of the body. Even as juveniles, the differences are obvious.
  • Images:
  • Silver Arowana (below left); Saratoga (below right)

 

Habitat information

• Silver Arowana are native to the floodplains of the Rupununi and Oyapock rivers in the Amazon River basin of Brazil, Colombia, Ecuador, Guyana, Franch Guiana and Peru.
• The Silver Arowana lives in a habitat of shaded water with branches and other dense cover.
• During flood time they move into the flooded forest and swim among the tree roots and branches. Their sinuous snake-like body means they are able to glide through and around snags easily.

Aquarium care
The following information relating to tank size, decoration and tank mates is indicative and intended to be used as a rough guide only. Other possible tank mates are listed under Compatibility and there are many plants and decorations that can be used - just ask us.

• How do you know if a Silver Arowana the right choice for your aquarium? If you answer Yes to the following questions, then you may be well on your way to keeping a Silver Arowana. Continue reading about how to care for an Arowana and consult with a WetPetz staff member to learn more. WetPetz is committed to responsible aquarium care.
  • Is my aquarium an appropriate size for the fish (remember that juveniles can be kept in a smaller tank - but you must be prepared to move them as they grow)?
  • If introducing to an established tank, is the Arowana compatible with other tank residents?
  • Do you have time to devote to looking after the Arowana?
  • Are you prepared to upgrade the tank to accomadate the size of the fish as it grows?
    
• Tank ideas....
  • Young fish 15 centimetres should not be kept in tank measuring less than 90 centimetres.
  • Fish measuring up to 40 centimetres should be kept in at least a 150 centimetre tank.
  • Eventually a considerably larger tank will be needed - 8 to 10 foot is a good size.
  • Example - Large Tropical South American "Community" tank:
    The effect recreated with this tank is of the flooded forest zone. The effect should be of random tangles of roots and branches of trees that have been submerged by flood waters.
  • Tank capacity: 460 litres
  • Tank type: HR-1800B
    • 180 centimetres (72 inches or 6 foot) tank
    • 1 x 40W; 2 x 30W; 2 x 20W fluorescent tubes
  • Fish ideas:
    • 1 x Osteoglossum bicirrhosum
    • 1 x Glyptoperichthys joseliaimanus
    • 5 x Myleus rubripinnis
  • Building the tank:
    • Background - external 3D Amazon tree trunck background.
    • Substrate - 3mm Coffs Harbour gravel 70kg.
    • Decoration - Driftwood. Add plenty of driftwood to create a shadowy labyrinth. Leave plenty of open swimming space as well.
      
    • Plants - Use plants strategically. Suitable plants include Dwarf Swordplant (Echinodoras tenellus); Hairgrass (Eleocharis acicularis); Amazon Swordplant (Echinodoras radicans) and Milfoil (Myriophyllum sp).
• Maintenance and Disease....
  • The tank must have a heavy, tight-fitting lid as the Silver Arowana will jump.
  • Good filtration is essental, although there should be minimal surface disturbance.
  • Regular partial water changes are needed - at least 30 percent once a fortnoght or more frequently as required.
  • When frightened, these fish are likely to swim frantically around the tank, throwing themselves against the tank cover and the tank sides. Often, self inflicted injuries result.
  • They appear to be susceptable to fin rot if the water conditions deteriorate. This is evidenced by ragged and frayed fins.
  • White spot may also be a problem if the water temperature is not warm enough.
  • Do not keep under crowded conditions as the fish will become stressed.
  • Water parameters:
    
    • pH: acidic to neutral (6.0-7.0)
      
    • Hardness: moderate (4-15dH: optimum 12)
      
    • Temperature: 24-28oC.
• Compatibility....
  • When young, these fish are easily harassed by more aggressive species such as Cichlids.
  • The most important criteria for tank mates is size, as Arowana will eat any fish that fits in its mouth.
  • The Silver Arowana is aggressive towards similar species and should be kept singly instead of in pairs or groups.
  • They should only be combined with large, robust species that inhabit the lower levels of the tank.

• Breeding....
  • The Silver Arowana forms pairs during the breeding season.
  • They are a mouthbrooder, with the male responsible for brood care.
  • The female produces 150 to 200 eggs, which are taken into his mouth after fertilisation.
  • The eggs are large, at around 1.2 centimetres in diameter.
  • The male holds the eggs and fry for several weeks.
  • After the yolk-sac is used up in 2 or 3 weeks, the male lets them out of his mouth to feed on microorganisms such as algae, tiny crustaceans, and insects.
  • Breeding males have bright pink spots on their cheeks, which attract females.
  • When danger threatens, the male's barbels are used to signal the young back into the safety of his mouth.
  • After 4 to 6 weeks, the young are abandoned to fend for themselves (juvenile Silver Arowana - right).

• References....
  Web sites
  Fishbase
  Books
  Baensch Aquarium Atlas Vol 2 (Tetra Press, 1997)
  

WetPetz
ph: (07) 3823 1866