Silver arowana
A metre-long surface predator that leaps clear of the water to take prey from overhanging branches, and a paternal mouthbrooder carrying its young for weeks. It is sold at ten centimetres and grows to a size only a purpose-built system can hold.
Quick profile
- Scientific name
- Osteoglossum bicirrhosum
- Adult size
- 90–120 cm (35.4–47.2 in)
- Lifespan
- 15–20 years
- Temperature
- 26–30 °C (79–86 °F)
- pH
- 5.5–7.2
- Hardness
- 1–10 °dGH
- Minimum tank
- 6000 L (1585 US gal)
- Minimum length
- 420 cm
- Swimming zone
- Surface
- Social
- Solitary
- Diet
- Carnivore
- Overall confidence
- moderate confidence
What keeping this species involves
A fish over a metre long that jumps, is sensitive to water quality and lives for two decades. It requires a system built for it and is sold as an ornamental juvenile.
Flooded forest and slow river margins, where the fish cruises immediately beneath the surface hunting insects and small vertebrates.
Identity and names
- Common name
- Silver arowana
- Scientific name
- Osteoglossum bicirrhosum
- Family
- Osteoglossidae
- Order
- Osteoglossiformes
- Class
- Actinopterygii
- Also sold as
- Osteoglossum bicirrhosum, arowana, dragon fish, water monkey
Adult size and growth
90–120 cm (35.4–47.2 in)
Typical lifespan in an aquarium: 15–20 years. Almost every animal sold in a shop is a juvenile, so the tank has to suit the size in the first line rather than the size in the bag.
Shape, which is what the compatibility engine reads instead of length alone: elongate with a very large — prey approaching its own length. A surface predator with an upturned jaw that opens the full depth of its head.
Water and tank requirements
A surface-hunting fish over a metre long that must be able to turn without striking the ends. Length and width are both constraints, and this figure describes a purpose-built system rather than an aquarium.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
Why these ranges: Amazonian flooded forest, warm and soft. The species is sensitive to poor water quality and to nitrate accumulation, which in a system holding a fish of this size is the main practical challenge.
Where these figures come from
Habitat class
Lowland floodplain
Seasonally inundated flat country — várzea, chaco, swamp margin — where the water body changes size, depth and chemistry through the year.
The habitat's defining feature is change, so a single band describes it badly. Species from here are generally tolerant of a wide range and intolerant of nothing much — which makes them easy to keep and easy to keep wrongly.
- Conductivity
- 40–300 µS/cm
- Flow
- still
- Dissolved oxygen
- low
- Seasonality
- strong
These are figures for the KIND of water body, not measurements of this species. They are AquariumHQ’s summary of the general limnology and are given wide because the water is.
- TemperatureReasoned on this record
- This record states its own reason for this band. See the water section.
- pHReasoned on this record
- This record states its own reason for this band. See the water section.
- General hardnessReasoned on this record
- This record states its own reason for this band. See the water section.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 26–30 °C (79–86 °F) | Stability matters more than hitting an exact figure. |
| pH | 5.5–7.2 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 1–10 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 6000 L (1585 US gal) | A floor, not a recommendation. |
| Minimum footprint | 420 cm long × 150 cm deep | A surface-hunting fish over a metre long that must be able to turn without striking the ends. Length and width are both constraints, and this figure describes a purpose-built system rather than an aquarium. |
| Water flow | low | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Open surface with a heavy, securely fastened cover. Decor near the surface causes injuries; the fish uses the top few centimetres of water almost exclusively. |
Behaviour
- Leaps clear of the water to take insects and small vertebrates from overhanging branches, which is where the name water monkey comes from.
- Cruises immediately beneath the surface with the body almost horizontal, using the upturned mouth to feed upward.
Telling males from females
No reliable external difference.
Feeding
Takes prey at and above the surface. Prepared food works well and live feeders add disease risk without benefit.
- Diet type
- Carnivore
- Staples
- Whole frozen fish, Prawn, Large floating pellets, Insects
- Avoid
- Live feeder fish, Mammalian meat
Breeding
- Strategy
- Paternal mouthbrooding of very large eggs for around two months
- Difficulty
- rarely achieved
- Parental care
- mouthbrooding
Broods are small and the young emerge several centimetres long with the yolk sac still attached.
Tankmates and compatibility
Assessments are derived from stored traits by the compatibility engine, with the reasoning shown. A verdict is a statement about probability, not a guarantee — individual temperament can override it.
| Towards | Risk | What it means |
|---|---|---|
| Small fish | near-certain | Anything that fits in the mouth is at risk once this species reaches adult size. |
| Adult dwarf shrimp | near-certain | Cover reduces losses but rarely prevents them where the risk is high. |
| Shrimplets | near-certain | Determines whether a shrimp colony can grow rather than merely persist. |
| Snails | moderate | Applies to snails you wanted as well as snails you did not. |
| Long or trailing fins | none | Fin damage is an entry point for secondary infection. |
| Plants | none | Tough species such as Anubias and Java fern survive most grazers. |
Assessed pairings
Any pair in the catalogue can be assessed with the compatibility checker.
Welfare considerations
Points where the way this species is commonly sold or kept differs from what it actually needs.
- Prone to a permanently deformed eye — the condition keepers call drop eye — which is associated with looking downward in a tank and with diet, and does not reverse.
- Jumps with enough force to displace an unsecured cover. Injuries from striking the lid are common and damage to the mouth and snout is often permanent.
Problems to watch for
Most problems in a tank containing this species are general rather than species-specific. Start with the troubleshooting index and work from the observation rather than from a guess at the cause.
What AquariumHQ does not yet hold
Species-level disease susceptibility is modelled in the graph and is not yet populated. Health pages will not be published until each condition has veterinary sourcing, because health content written without evidence is the most harmful thing this product could publish. The gap is recorded in the coverage report.
Where it comes from
- Native range
- The Amazon basin and the Rupununi and Oyapock drainages of the Guianas
- Habitat
- Flooded forest and slow river margins, where the fish cruises immediately beneath the surface hunting insects and small vertebrates.
What the checklists say
21 distribution statements retrieved from GBIF checklists. Establishment means is reproduced from the source where it states one, and left unstated where it does not — a record of presence is not a record of origin.
| Status | Places | What this means |
|---|---|---|
| Native | 6 | A checklist states the species occurs here naturally. |
| Introduced | 7 | A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal. |
| Recorded as present, establishment means not stated | 8 | The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in. |
Legal status and responsible practice
Restriction note
This species is not itself CITES-listed, but the Asian arowana Scleropages formosus is on Appendix I and is prohibited or licence-controlled in many countries. The two are sold under overlapping names, and a fish described only as an arowana may be either.
Never release aquarium life into the wild
Aquarium animals, plants, and aquarium water must never be released into ponds, rivers, canals, drains or the sea — not even in a country where the species is sold freely. Released fish and invertebrates establish populations that displace native species, and released plants and water carry pathogens, parasites and fragments capable of spreading without any animal at all. If you can no longer keep an animal, rehome it through an aquarium society, a retailer that accepts returns, or another keeper.
- Rehome through a local aquarium society, a specialist retailer or another keeper.
- Unwanted plants go in household waste or a hot compost heap, never in a watercourse or a garden pond.
- Never empty a bucket of tank water into a drain that discharges to open water.
- If an animal is beyond rehoming, ask an aquatic veterinarian about humane euthanasia rather than releasing it.
Legal status is recorded from the sources named and was correct on the verification date shown. Rules change, and sub-national rules often differ from national ones. Check the current position with the relevant authority before acquiring, selling or moving any animal or plant.
Evidence
Every stored value with the kind of support behind it and where to check it. Evidence type and confidence are separate axes: an editorial position held confidently and a measurement held tentatively are different things.
| Claim | Value | Evidence type | Confidence | Source |
|---|---|---|---|---|
| scientific name | Osteoglossum bicirrhosum | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | The Amazon basin and the Rupununi and Oyapock drainages of the Guianas | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 90–120 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 15–20 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 26–30 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 5.5–7.2 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 1–10 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 6000 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 420 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
Last reviewed 2026-08-10. Values labelled as an aquarium-literature consensus are AquariumHQ editorial positions rather than measurements — see how evidence is handled.
Why we say this
What each figure on this page rests on, and how far that is from being independently established.
Every figure on this page has a provenance. Open any claim to see what AquariumHQ holds for it, which sources say what, and what a claim of that kind actually needs. Different claims need different evidence: an accepted scientific name is settled by one authority, while a legal restriction needs a current primary instrument. A single source is often the right answer rather than a thin one.
scientific nameAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: accepted scientific name and classification — 1 authoritative source in an appropriate context. Checked against gbif on 2026-08-29. One authoritative backbone is what this class requires.
What would improve this: Go and read a source. This is reachable and has not been reached.
native rangeAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: where the species occurs — 1 authoritative source in an appropriate context. 21 distribution statements held from GBIF checklists — native in 6, introduced in 7 countries. Establishment means is reproduced from the source, never inferred from occurrence.
What would improve this: Go and read a source. This is reachable and has not been reached.
adult sizeAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
lifespanAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
temperatureAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
phAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
general hardnessAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
minimum tank volumeAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
minimum tank lengthAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
Guides relevant to this species
Chosen from this record's own traits rather than listed on every page.
- Predator and prey sizeIt takes fish that fit in its mouth, and its mouth grows with it.
- Territorial behaviourIt defends ground, and the shape of what it defends decides the tank more than the volume does.
- Native, introduced and invasiveThis record carries an invasive or legal note, and those are five separate claims that are easy to read as one.
- Wild conditions and aquarium recommendationsThe water band on this page is an AquariumHQ position with a stated reason, not a measurement of a river.
- Rehoming an animal you can no longer keepThis animal reaches 120 cm. Most of the difficult rehoming cases are fish sold small that were always going to become impossible.
Group size and social behaviour
Aggressive towards its own kind in anything short of a very large system. Kept singly in almost all cases.