Arowana Fish Care — The Complete Guide to Asian and Silver Arowana in India

By ProHobby™ | Ecological Systems Authority

No fish in the ornamental trade carries the regulatory complexity, the cultural weight, and the genuine biological distinctiveness of the arowana. At one end of the spectrum sits the silver arowana — a freely traded South American river predator with no legal complication whatsoever. At the other end sits the Asian arowana — a CITES Appendix I species whose legal international trade exists only because of a deliberate, decades-long conservation and captive-breeding programme that is, in itself, one of the more remarkable case studies in ornamental fish regulation. Most guides flatten this into a single warning sentence and move on to generic large-fish care advice. This guide does not. It covers the biology of both species in real depth, the actual mechanics of how Asian arowana legality works, the science behind why colour develops the way it does, and the husbandry detail that separates a thriving arowana from a stunted, stressed, or legally compromised one.

Table of Contents

1. The Osteoglossidae Lineage — Why Arowana Are Biologically Unusual
2. Silver Arowana — Natural History and Behaviour
3. Asian Arowana — The CITES Appendix I Story in Full
4. How the Captive-Breeding and Microchip System Actually Works
5. Asian Arowana Varieties — The Genetics and Geography Behind Each Colour
6. The Biology of Arowana Colour Development
7. Tank Requirements — Engineering for a Surface Predator
8. Water Parameters and Why They Matter Differently for Each Species
9. Filtration and Bioload Management
10. Feeding — Biology, Practice and the Pellet Transition
11. Growth Rate and Long-Term Size Planning
12. Drop Eye — Full Mechanism, Prevention and Why It Cannot Be Reversed
13. Stress Bars — The Physiology Behind the Visible Sign
14. Common Diseases in Depth
15. Sexing — Why It Is Genuinely Unresolved at the Hobbyist Level
16. Compatibility and Tank Mate Selection
17. Vastu Shastra and Feng Shui — The Cultural Mechanics of Demand
18. Arowana Price in India — What Actually Drives the Numbers
19. India and Delhi NCR — The Supply Chain Reality
20. Frequently Asked Questions

1. The Osteoglossidae Lineage — Why Arowana Are Biologically Unusual

Arowanas belong to the family Osteoglossidae — the “bony-tongued fishes” — one of the oldest surviving lineages of bony fish on the planet, with fossil relatives dating back over 100 million years to the Cretaceous period. The family name describes a genuinely unusual anatomical feature: arowana possess a bony structure on the floor of the mouth (the basihyal) that works against toothed structures on the roof of the mouth to crush and process prey — a tongue that is, functionally, a second set of jaws made of bone.

This ancient lineage today survives as a small number of genera scattered across South America, Africa, Southeast Asia, and Australia — a distribution pattern called a Gondwanan relict, reflecting the breakup of the ancient southern supercontinent over 100 million years ago. Osteoglossum (the South American silver and black arowanas) and Scleropages (the Asian and Australian arowanas) are separated by an entire ocean and tens of millions of years of independent evolution, yet they converge on an almost identical body plan and predatory strategy: elongated, laterally compressed bodies, an upturned mouth adapted for surface feeding, and an extraordinarily well-developed lateral line system that detects the faintest surface disturbance from insects, small vertebrates, or falling debris.

This shared ancestry and convergent design is why silver and Asian arowana — despite never encountering each other in the wild — have nearly identical husbandry requirements, behaviour, and disease susceptibility, while differing entirely in their legal status.

2. Silver Arowana — Natural History and Behaviour

Osteoglossum bicirrhosum inhabits the slow-moving blackwater and whitewater systems of the Amazon and Orinoco basins, particularly the seasonally flooded forest (várzea and igapó) zones where the boundary between river and forest floor disappears for months at a time during high water. In these flooded forest conditions, silver arowana hunt at the surface beneath the forest canopy, taking insects, spiders, and small vertebrates that fall or are knocked from overhanging vegetation — a foraging strategy enabled by their acute surface-disturbance detection.

Two small barbel-like projections on the lower jaw (visible in both silver and Asian arowana) are believed to function as additional sensory structures, possibly chemosensory, supplementing the lateral line’s mechanical detection. Silver arowana are also documented to leap clear of the water to take prey directly from overhanging branches — a behaviour with direct relevance to captive keeping, since the same leaping instinct is what causes arowana to clear open-top aquariums.

In the wild, silver arowana reach lengths exceeding 1 metre, though captive specimens in well-maintained but space-constrained aquaria typically max out in the 60–90 cm range over several years, with growth continuing more slowly beyond that point.

3. Asian Arowana — The CITES Appendix I Story in Full

Scleropages formosus is native to the river systems and peat swamp forests of Peninsular Malaysia, Sumatra, Borneo, and parts of Thailand and Cambodia. Wild populations declined dramatically through the mid-to-late 20th century from a combination of habitat destruction — particularly the drainage and conversion of peat swamp forest, one of the most threatened habitat types in Southeast Asia — and intense collection pressure once the species became established as a high-value ornamental fish in Chinese and broader East and Southeast Asian markets, where it acquired deep cultural significance as a symbol of prosperity (see Section 17).

This combination led to the species being listed on CITES Appendix I in 1975 at the Convention’s founding, placing it in the same legal category as species such as tigers and elephants — commercial international trade in wild specimens is prohibited outright, with no exceptions for any purpose.

The captive-breeding pathway that followed is the part of the story most guides omit entirely. Recognising both the conservation imperative and the reality of sustained high commercial demand, several countries — Singapore first and most significantly, followed by Malaysia and Indonesia — developed government-regulated captive-breeding programmes specifically to satisfy CITES requirements for legal international trade in a Appendix I species. This is permitted under CITES Article VII, which allows trade in specimens bred in captivity for commercial purposes at a registered, CITES-approved operation, provided each individual fish is uniquely and permanently marked and the entire breeding stock and lineage is auditable by CITES Secretariat-recognised authorities.

The microchip system exists specifically to satisfy this requirement. Each captive-bred Asian arowana legally entering international trade has a passive integrated transponder (PIT) microchip implanted, typically in the dorsal musculature, before export. The microchip number is recorded on the CITES export permit issued by the exporting country and the corresponding import permit issued by the importing country’s CITES Management Authority. This creates a continuous, individually traceable chain of custody from the registered breeding farm to the final buyer — in principle, any documented Asian arowana can be scanned and its number cross-referenced against the paper trail at any point in its life.

This is also exactly why undocumented Asian arowana in markets like India’s are unambiguously illegal under the framework, with no grey area. A fish without a microchip, or with a microchip number that cannot be matched to valid CITES paperwork, has no legal pathway into the country regardless of how it is described by the seller. India is a signatory to CITES and implements it domestically; the Wildlife Protection Act and associated customs and wildlife trade regulations treat unauthorised possession of a CITES Appendix I specimen as a serious offence.

4. How the Captive-Breeding and Microchip System Actually Works

It is worth understanding the mechanics in more depth, both to appreciate why legitimate Asian arowana command such high prices and to recognise what genuine documentation should look like.

Registered farms — the most internationally recognised being long-established Singaporean and Malaysian operations — maintain closed breeding populations originally founded from legally collected or historically held broodstock, predating or specifically authorised under the CITES framework. Breeding Asian arowana in captivity is genuinely difficult: the species is a mouth-brooder, meaning the male carries fertilised eggs and newly hatched fry in his mouth for several weeks, during which the pair must be left largely undisturbed, fry survival rates are inconsistent, and the fish do not reach breeding maturity for several years. This biological difficulty, combined with the regulatory overhead of CITES-compliant breeding operations, is a major structural reason supply remains limited and prices remain high even for legally unremarkable colour varieties.

Once fry reach a minimum viable size, each fish is implanted with a microchip, photographed, and registered with the relevant national CITES Management Authority before any export permit is issued. The importing country’s CITES authority then issues a corresponding import permit before the fish can legally clear customs. At the retail level, a buyer should be able to request to see both permits and have the microchip scanned and the number matched against the documentation — this is the only reliable verification method, and any seller unable to facilitate it is not selling a documented fish.

5. Asian Arowana Varieties — The Genetics and Geography Behind Each Colour

The colour varieties recognised in the Asian arowana trade are not arbitrary marketing categories — they correspond to genuine, geographically distinct wild populations that were brought into the captive-breeding programmes and have since been maintained and intensified as largely separate breeding lines.

Super Red traces to populations from the Kapuas River system in West Kalimantan, Indonesian Borneo. The red colouration in this lineage is the most intensely developed of any Asian arowana variety, typically beginning to show in the fins and gradually spreading and deepening across the body and head over 3–5 years as the fish matures — a slow, cumulative process rather than a fixed juvenile trait, which is part of why mature, fully coloured specimens command such elevated prices relative to juveniles of uncertain final colour potential.

Golden Crossback derives primarily from the Bukit Merah reservoir population in Perak, Malaysia — itself the product of an unusual conservation history in which a wild population became isolated and subsequently the foundation stock for Malaysia’s captive-breeding industry. The defining “crossback” trait — gold scale colouration extending dorsally above the lateral line line, rather than remaining confined below it — is a genetically distinct and more strongly expressed form than the related Red Tail Golden variety, and is graded heavily on how far up the back the gold extends and how reflective the scale colour appears.

Red Tail Golden (RTG) is generally understood within the trade to derive from related but distinct Indonesian and Malaysian gold-line populations, producing gold body colouration that does not cross above the lateral line, paired with a reddish tail — a combination considered a step below true Crossback in the grading hierarchy but still a recognised and valued variety in its own right.

Green and Banjar varieties retain colouration closest to ancestral wild-type Asian arowana — a more subdued bronze-green — and are generally the most genetically unmodified, hardiest, and most affordable legally documented entry point into Asian arowana keeping.

6. The Biology of Arowana Colour Development

Colour intensity in Asian arowana — and to a lesser, less commercially scrutinised extent in silver arowana — develops through the deposition and arrangement of pigment cells (chromatophores) within and beneath the scales, a process that continues actively for years after the fish reaches its adult length. This is fundamentally different from many ornamental fish where adult colouration is essentially fixed shortly after maturity.

Three factors are understood within serious arowana-keeping circles to meaningfully influence the rate and final intensity of colour development, beyond baseline genetics:

Water chemistry — slightly soft, slightly acidic water more closely matching the fish’s native peat swamp and blackwater habitats is associated with more vigorous colour development than hard, alkaline water, which is part of why RO blending is recommended for serious Asian arowana keepers in hard-water regions, distinct from the general health argument for correct water chemistry.

Lighting — full-spectrum lighting including appropriate UV-A wavelengths is believed to support more complete chromatophore development, and many dedicated arowana keepers use lighting specifically marketed for this purpose, positioned to illuminate the fish from the side rather than only from directly above.

Diet — diets including carotenoid-rich foods (certain prawns, specific commercial arowana colour-enhancing pellets) are widely used on the understanding that carotenoid pigments contribute directly to red and orange colour expression, the same general principle underlying colour-enhancing diets in many other ornamental fish and in flamingos and salmonids in the wild.

None of these factors override genetics — a Green/Banjar specimen will not develop Super Red colouration regardless of water, light, or diet — but within a given variety’s genetic ceiling, husbandry quality measurably affects how close a fish comes to its potential, which is precisely why chronic stress bars (Section 13) are taken so seriously by colour-focused keepers.

7. Tank Requirements — Engineering for a Surface Predator

Minimum tank size for a single adult arowana of either species: 500–600 litres, with a footprint of at least 180 cm length by 60 cm width. The length requirement is non-negotiable and reflects the fish’s natural swimming pattern — arowana cruise in long, sweeping passes near the surface rather than using vertical space, making a long, comparatively shallow tank biologically more appropriate than a tall one of equivalent volume.

Glass thickness and structural engineering matter more for arowana than for almost any other commonly kept fish, given the combination of large adult size, high water volume, and the explosive force of jumping behaviour against the tank lid. Mass-produced, minimally specified tanks are a genuine risk for a fish this size over a multi-year keeping period — the Glass Thickness Calculator is directly relevant when commissioning or selecting a tank for an arowana of either species, and custom-fabricated tanks with correctly specified glass and structural bracing are the appropriate standard for an investment-grade fish kept over many years. Aquarium Shop Delhi NCR — What a Specialist Looks Like covers what correct tank fabrication looks like versus the mass-produced alternative.

Lid security deserves emphasis beyond the standard advice to “use a heavy lid.” Arowana jumping is not an occasional startled reaction — it is a hard-wired surface-feeding strike behaviour that can be triggered by overhead movement, insects near the water surface, or apparently no stimulus at all, and a fish of 60+ cm striking upward generates substantial force. The lid must be both heavy and mechanically secured against being displaced from below, not merely resting in place.

8. Water Parameters and Why They Matter Differently for Each Species

Both species tolerate this range adequately for basic health, but the practical emphasis differs. For silver arowana, water chemistry management is primarily about avoiding the ammonia toxicity risk created by their substantial bioload (Section 9) — the fish itself is relatively unfussy about pH and hardness within a broad tropical range. For Asian arowana, water chemistry carries the additional dimension covered in Section 6: serious keepers manage toward the softer, more acidic end of the tolerable range specifically to support colour development, not merely to avoid acute harm. Ammonia in Aquariums covers the toxicity mechanism relevant to either species.

9. Filtration and Bioload Management

Arowana of either species are large, frequent, messy feeders producing a bioload disproportionate to many other fish of similar adult length, because their carnivorous diet and feeding volume generate substantial nitrogenous waste. External canister filtration rated for 8–10× total tank volume turnover per hour is the appropriate baseline, with the expectation that filtration will need to scale further as the fish approaches adult size — a juvenile-appropriate filter sized at purchase will be inadequate within 12–18 months given the growth trajectory in Section 11.

Weekly substrate vacuuming and attentive monitoring of mechanical filtration media (which clogs faster than in lower-bioload tanks) are standard maintenance requirements rather than optional extras. How to Clean an Aquarium Filter Without Killing Bacteria is directly applicable, since the biological filtration load in a mature arowana tank is significant enough that careless cleaning genuinely risks an ammonia event.

10. Feeding — Biology, Practice and the Pellet Transition

Both species are obligate carnivores adapted to surface and near-surface predation, and their feeding response is visually dramatic — a healthy arowana will strike forcefully at food presented at or near the surface, a behaviour directly continuous with their wild surface-feeding strategy.

Juvenile diet (under 30 cm): Crickets, mealworms, earthworms, appropriately sized feeder fish, and large pellets formulated for predatory fish. Live food at this stage supports the development of normal feeding strike behaviour, but exclusive reliance on live feeder fish of unknown origin introduces genuine parasite risk (see Section 14).

Adult diet: Large predatory pellets, whole prawns, fresh fish fillets, occasional earthworms. The transition away from a primarily live-food diet toward a primarily pellet-based one is both a health and practicality consideration — pellet-fed arowana have more predictable nutrition, lower parasite exposure, and are dramatically easier to feed consistently over a multi-year keeping period than a fish dependent on a constant live food supply.

The pellet transition technique: Withhold live or fresh food for 2–3 days — a period well within the fish’s tolerance for short-term fasting — then offer large, high-quality predatory pellets at the surface where the fish’s feeding instinct is triggered. Most arowana accept pellets within a week using this method; persistence beyond the first attempt is normal and should not be read as the fish rejecting pellets permanently.

Feeding frequency: Once daily for juveniles supporting active growth; every other day for adults, reflecting their slower adult metabolic demand relative to body size.

11. Growth Rate and Long-Term Size Planning

Both silver and Asian arowana display a growth pattern that catches unprepared keepers off guard: a juvenile purchased at 10–20 cm can add 5–7 cm of length per month under good conditions during the first 12–18 months, meaning a fish that looked entirely manageable in a starter tank can require its full adult tank specification well within its first two years of life — long before most keepers have built or sourced the eventual 500+ litre system this guide specifies in Section 7.

Adult length for both species typically settles in the 60–90 cm range in captivity, with silver arowana having a somewhat higher documented ceiling than most Asian arowana varieties, though individual variation within either species is considerable. The practical implication is unambiguous: the adult tank should be planned and ideally ready before a juvenile arowana of either species is purchased, not after.

12. Drop Eye — Full Mechanism, Prevention and Why It Cannot Be Reversed

Drop eye deserves more explanation than the single-sentence treatment it usually receives, because understanding the actual mechanism is what makes prevention intuitive rather than arbitrary.

The condition arises from sustained, habitual downward gaze — the fish consistently orienting its eyes downward over weeks to months, typically because it is repeatedly looking down at activity below it: food being dropped from above, the keeper’s movement viewed from below when standing over the tank, or simply a behavioural pattern that develops in tanks where the most visually interesting stimuli are consistently positioned below the fish’s natural eye line. Over this sustained period, remodelling occurs in the soft tissue and supporting structures around the eye socket, progressively shifting the resting orientation of the eye itself downward. Because this is a genuine structural remodelling of orbital tissue rather than a temporary muscular position, it does not reverse once established — the eye has, in effect, been physically reshaped into its new resting orientation.

Prevention is entirely about controlling what the fish habitually looks at. Positioning the tank so the fish’s most consistent visual stimuli — keeper movement, feeding, general room activity — occur at or above the fish’s eye level rather than below it removes the trigger for sustained downward gaze. This is a specific reason many serious arowana keepers avoid tall display stands that put the tank well below standing eye height, and avoid feeding exclusively from directly above the water surface.

For Asian arowana specifically, drop eye carries an additional dimension beyond general welfare: it measurably and permanently detracts from the fish’s symmetry and presentation, directly affecting its value within the variety-and-condition grading culture described in Section 5.

13. Stress Bars — The Physiology Behind the Visible Sign

Stress bars are dark vertical bands that appear across the body when an arowana of either species experiences acute fear, environmental disruption, or sustained low-level stress. The mechanism is the same general chromatophore response seen across many fish species under cortisol-mediated stress signalling — the same hormonal pathway covered in depth in The Science of Fish Stress — but the visible effect in arowana is particularly pronounced and easy to observe given their large, clearly visible scales.

Common triggers: relocation to a new tank, sudden lighting changes, perceived predator activity near the tank (cats, sudden movement, children running past), water parameter fluctuation, and incompatible or overcrowded tank mates.

Stress bars appearing in a newly introduced arowana are an expected, transient response and typically fade within 1–3 weeks as the fish acclimates. Persistent stress bars in an established fish are a different signal entirely — they indicate an ongoing, unresolved environmental stressor that requires active identification rather than patience, and for Asian arowana, chronic stress bars are understood within the keeping community to also measurably suppress the colour development process described in Section 6, making their resolution doubly important for colour-focused keepers.

14. Common Diseases in Depth

Ich is common in stressed or recently transported arowana of either species, given the long supply chains many specimens — particularly imported ones — pass through before reaching an Indian buyer. Ich — White Spot Disease Treatment Guide applies directly, with dosing calculated carefully against the fish’s substantial individual water volume.

Gill flukes are a frequent introduction with new arowana and present with the flashing and rubbing behaviour typical of the condition generally. Gill Flukes — Treatment Guide.

Fin and scale damage from jumping against tank lids or walls during stress responses creates open wounds that are then vulnerable to secondary bacterial colonisation — Columnaris and the gram-negative bacteria responsible for scale rot both readily establish at these injury sites in a fish this large, and any wound should be monitored closely in the days following an incident.

Internal parasites, given the live-food-heavy diet common particularly in juvenile arowana feeding, are a real consideration — Internal Parasites in Aquarium Fish and Capillaria and Internal Nematodes both apply, particularly for arowana fed extensively on live feeder fish or invertebrates of uncertain origin rather than transitioned to pellets as recommended in Section 10.

15. Sexing — Why It Is Genuinely Unresolved at the Hobbyist Level

Visual sexing of arowana — either species — remains genuinely unreliable outside of direct observation of breeding behaviour or, in the case of registered Asian arowana breeding farms, controlled conditions where pairing and mouth-brooding can be directly observed. Mature females are sometimes described as having a fuller body profile, and males are sometimes described as having a marginally larger or broader mouth — plausibly related to the male’s mouth-brooding role in Asian arowana specifically — but neither characteristic is consistent or reliable enough to constitute genuine sexing at the point of purchase or in a typical hobbyist setting. Claims of confident visual sexing from sellers should generally be treated with appropriate scepticism.

16. Compatibility and Tank Mate Selection

Adult arowana of either species are predatory toward anything that fits within their mouth, which given their adult size is a considerable range of smaller fish. Appropriate tank mates are restricted to species both too large to be eaten and robust enough to tolerate the arowana’s dominant presence and occasional territorial behaviour: large oscars, large armoured catfish (sailfin plecos, Pangasius species), and other large, similarly robust cichlids. No genuinely peaceful or small community species should ever be introduced to an adult arowana tank of either species, regardless of how the arowana’s temperament is described.

17. Vastu Shastra and Feng Shui — The Cultural Mechanics of Demand

The cultural significance driving Asian arowana demand specifically — rather than ornamental fish demand generally — deserves explanation rather than a passing mention, because it is the actual economic engine behind both the legitimate high-end Asian arowana trade and the illegitimate undocumented trade that coexists alongside it in India.

Within Chinese cultural tradition, predating its adoption into broader Southeast Asian and South Asian Feng Shui and Vastu practice, the Asian arowana’s red and gold colouration and elongated, scaled body bear a visual resemblance to the mythological dragon — a creature strongly associated with imperial power, prosperity, and protective strength. This “dragon fish” association, combined with the fish’s substantial cost (itself read as a marker of the keeper’s prosperity, in a self-reinforcing cultural loop), cemented Asian arowana as one of the most significant single ornamental fish species associated with wealth attraction in Feng Shui practice, an association that has carried directly into Indian Vastu Shastra interpretation as the species became known and desired in the Indian market.

Silver arowana carries related but distinctly less specific symbolism — it shares the general form and behaviour but lacks the particular colour and cultural lineage that makes Asian arowana the singular “dragon fish” of Feng Shui and Vastu tradition specifically. Full placement, direction, and species guidance: Vastu Shastra & Feng Shui.

18. Arowana Price in India — What Actually Drives the Numbers

Silver arowana: Juveniles (10–15 cm) ₹800–2,500; adults (40–60 cm) ₹3,000–10,000+. Pricing reflects straightforward supply and demand for a freely traded species with no regulatory premium.

Documented Asian arowana: Pricing reflects the layered cost structure described throughout this guide — the genuine breeding difficulty and limited supply from registered farms (Section 4), the variety-specific genetic lineage and colour grading (Section 5), and the CITES compliance and microchip documentation overhead. Entry-level documented Green/Banjar specimens can begin in the tens of thousands of rupees; premium documented Super Red and Golden Crossback specimens with strong colour development and verified lineage frequently reach into six figures.

Undocumented Asian arowana: Typically priced attractively relative to documented specimens of the equivalent claimed variety — and this gap is itself the clearest available signal of risk, reflecting both the absence of the genuine compliance overhead and, frequently, lower quarantine and husbandry standards in the supply chain behind such fish.

19. India and Delhi NCR — The Supply Chain Reality

Demand for Asian arowana in Delhi NCR specifically is substantial and driven heavily by the Vastu and Feng Shui motivations detailed in Section 17, across both residential buyers and commercial establishments seeking the wealth-attraction symbolism for business premises. This sustained demand has supported a parallel undocumented supply chain that hobbyists should approach with the legal caution detailed in Sections 3 and 4 — verification of CITES permits and microchip registration is the only reliable safeguard, and its absence should be treated as definitive rather than as a negotiable detail.

A limited number of specialist importers maintain genuine, auditable CITES documentation chains for Asian arowana entering the Indian market; fish sourced through these channels carry verifiable paperwork and a scannable microchip, and their pricing reflects the genuine scarcity and compliance cost of legitimate supply. Aquarium Shop Delhi NCR — What a Specialist Looks Like covers the broader framework for evaluating any supplier’s certification claims, directly applicable to CITES-listed species sourcing.

Delhi NCR’s hard, alkaline tap water sits outside the ideal range for either species and specifically outside the range associated with optimal Asian arowana colour development (Section 6); partial RO blending is the practical recommendation for serious keepers of either species, with particular relevance for Asian arowana owners focused on colour outcomes. Hard Water Aquariums in Delhi NCR.

Frequently Asked Questions

Is Asian arowana legal in India? Only with verified CITES export and import permits and a matching, scannable microchip confirming captive-bred origin from a CITES-registered farm. The microchip system exists specifically to make every legally traded Asian arowana individually traceable; a fish without this documentation has no legal pathway into India regardless of how it is described or sold, and possession without it is a Wildlife Protection Act and CITES compliance violation.

What is the actual difference between Asian arowana and silver arowana? Both belong to the ancient Osteoglossidae lineage and share nearly identical body plan, surface-predatory behaviour, and husbandry needs. Asian arowana (Scleropages formosus) is native to Southeast Asian peat swamp and river systems, develops the red and gold colour varieties prized in Feng Shui and Vastu tradition, and is CITES Appendix I protected with trade permitted only from registered captive-breeding farms. Silver arowana (Osteoglossum bicirrhosum) is native to South America, remains silver throughout life, and is entirely unrestricted in trade.

Why do Asian arowana have microchips? The microchip is the mechanism that makes CITES-compliant captive-bred trade in an Appendix I species possible at all. Each fish is individually and permanently marked before export, with the chip number recorded against the CITES export and import permits — creating an auditable chain of custody from the registered breeding farm to the buyer. Scanning the chip and matching it against the paperwork is the only reliable way to verify a fish’s legal status.

Why does Asian arowana colour develop slowly over years rather than appearing immediately? Colour intensity in Asian arowana develops through ongoing chromatophore (pigment cell) deposition that continues actively for years after the fish reaches adult length, unlike many ornamental fish where colour is essentially fixed at maturity. Water chemistry, lighting, diet, and stress levels all measurably influence how fully a fish develops toward its genetic colour ceiling, which is why juveniles of even premium varieties show limited colour and why chronic stress bars are taken seriously by colour-focused keepers.

What tank size does an arowana need and why does length matter more than volume? Minimum 500–600 litres with at least 180 cm of length for an adult of either species. Length matters more than depth because arowana are surface-cruising swimmers by natural behaviour, not vertical swimmers — a long, comparatively shallow tank more closely matches how the fish actually uses space than a tall tank of equivalent total volume.

Can drop eye in arowana be fixed? No. Drop eye results from genuine structural remodelling of the tissue around the eye socket caused by sustained habitual downward gaze, not a temporary muscular position. Once the remodelling has occurred, it does not reverse. Prevention — positioning the tank so the fish’s habitual visual focus is at or above eye level rather than below — is the only effective approach.