Iridescent shark
A migratory river catfish farmed across South-East Asia for food and sold to aquarists at 5 cm. It reaches well over a metre, is not a shark, and is one of the clearest examples in the trade of a fish sold into a tank that cannot hold a tenth of it.
Quick profile
- Scientific name
- Pangasianodon hypophthalmus
- Adult size
- 100–130 cm (39.4–51.2 in)
- Lifespan
- 15–20 years
- Temperature
- 22–28 °C (72–82 °F)
- pH
- 6.5–7.5
- Hardness
- 4–20 °dGH
- Minimum tank
- 5000 L (1321 US gal)
- Minimum length
- 460 cm
- Swimming zone
- Midwater
- Social
- Shoaling — at least 4
- Diet
- Omnivore
- Overall confidence
- moderate confidence
What keeping this species involves
Its requirements are not difficult so much as unavailable: a tank in the thousands of litres, strong current, and a shoal of fish each over a metre long.
Large river channels, migrating substantial distances seasonally.
Identity and names
- Common name
- Iridescent shark
- Scientific name
- Pangasianodon hypophthalmus
- Family
- Pangasiidae
- Order
- Siluriformes
- Class
- Actinopterygii
- Also sold as
- striped catfish, sutchi catfish, pangasius, Pangasianodon hypophthalmus
- Former or synonymous names
- Pangasius hypophthalmus, Pangasius sutchi
Adult size and growth
100–130 cm (39.4–51.2 in) — Documented to around 130 cm. Sold at 4–6 cm. Even the growth achieved in a domestic tank — commonly 40–60 cm within a few years — exceeds almost every home aquarium.
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: fusiform — the ordinary torpedo with a large — a piscivore's mouth. A large-mouthed river pangasiid.
Water and tank requirements
A migratory shoaling river fish over a metre long needs a run measured in metres. The figures here are what the animal requires, not what a domestic tank can offer, and for most keepers the honest conclusion is that this species does not belong in one.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
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.
- TemperatureFollows the habitat this animal comes from
- Follows the water this animal is recorded from — lowland floodplain. Lowland floodplain generally runs 22–32°C, and the advised band of 22–28°C is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species.
- pHFollows the habitat this animal comes from
- Follows the water this animal is recorded from — lowland floodplain. Lowland floodplain generally runs 6–7.5, and the advised band of 6.5–7.5 is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species.
- General hardnessFollows the habitat this animal comes from
- Follows the water this animal is recorded from — lowland floodplain. Lowland floodplain generally runs 2–12 dGH, and the advised band of 4–20 dGH is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species.
Scale: 20.5 to 33.5 °C.
Scale: 5.8 to 7.7 pH.
Scale: -0.7 to 22.7 dGH.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 22–28 °C (72–82 °F) | Stability matters more than hitting an exact figure. |
| pH | 6.5–7.5 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 4–20 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 5000 L (1321 US gal) | A floor, not a recommendation. |
| Minimum footprint | 460 cm long | A migratory shoaling river fish over a metre long needs a run measured in metres. The figures here are what the animal requires, not what a domestic tank can offer, and for most keepers the honest conclusion is that this species does not belong in one. |
| Water flow | high | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Open water with strong current and no sharp decor. It panics and injures itself against hard surfaces. |
Behaviour
- Swims continuously and does not rest on the bottom.
- Startles violently and collides with tank walls and decor, which is how most captive injuries happen.
Feeding
- Diet type
- Omnivore
- Staples
- Large sinking pellets, Frozen prawn and mussel, Vegetable matter
Breeding
- Strategy
- Migratory river spawning, achieved commercially only by hormone induction
- Difficulty
- rarely achieved
- Parental care
- none
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 | uproots | 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.
- Sold at 5 cm with no mention of adult size. The fish outgrows a domestic aquarium within a couple of years, and rehoming one is close to impossible — public aquaria and rescues are routinely offered more than they can take.
- Poor eyesight combined with a strong startle response means it injures its snout and flanks against glass and decor.
- Released or dumped when outgrown. It is established outside its native range in several countries as a result.
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
- Mekong and Chao Phraya basins, widely farmed and introduced elsewhere
- Habitat
- Large river channels, migrating substantial distances seasonally.
What the checklists say
26 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 |
|---|---|---|
| Introduced | 20 | 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 | 6 | The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in. |
No checklist AquariumHQ holds positively calls this species native anywhere, so the native range above rests on AquariumHQ’s own reading of the literature rather than on a cited checklist.
Legal status and responsible practice
Restriction note
Farmed and traded internationally for food as well as for aquaria, and established outside its native range in several countries. Import and keeping rules differ between jurisdictions and are not established here; check the position with the relevant national authority before acquiring one.
Where this species has been introduced, and what followed
Two databases on two continents hold records for this species, and they are not two accounts of one event. They are separate introductions with separate causes, and the differences between them are the most informative thing on this panel.
Florida
Establishment unclearRoute unknown; NAS records aquarium release as likely, the species being common in the trade.
- Deliberate aquarium releaseSomebody took the animal out of a tank and put it into open water. The commonest reason is that the fish outgrew the aquarium, which is why size at maturity is a conservation question as well as a welfare one.
What has been established
Nothing. The species is present outside its native range and no study has measured what it does there. The absence of data is not the absence of effect — it means the question has not been asked, and this is the ordinary state of the evidence for most aquarium species that have established somewhere warm.
Sold at 5 cm and reaching 130. The release pathway for this species is almost entirely about size at maturity rather than about anything the keeper intended.
USGS Nonindigenous Aquatic Species database · Species Profile — Means of Introduction; Species Profile — Impact of Introduction · read 2026-08-29. A United States database: the routes and effects recorded here are the ones documented there, and say nothing about other regions.
Europe — a single record from Poland
Recorded, not establishedOne country, one pathway — pet and aquarium species, flagged LOW uncertainty — and no first-introduction date. This is what a released aquarium fish looks like in a database when it does not establish: a record, not an invasion.
- Deliberate aquarium releaseSomebody took the animal out of a tank and put it into open water. The commonest reason is that the fish outgrew the aquarium, which is why size at maturity is a conservation question as well as a welfare one.
What has been established
Nothing. The species is present outside its native range and no study has measured what it does there. The absence of data is not the absence of effect — it means the question has not been asked, and this is the ordinary state of the evidence for most aquarium species that have established somewhere warm.
A fish sold at 8 cm that reaches over a metre and is a shoaling river migrant. The Polish record is one animal's worth of evidence that people do let them go.
EASIN — European Alien Species Information Network · EASIN catalogue record R20101 (apixg/catxg) · read 2026-08-30. A European network: the routes and effects recorded here are the ones documented in Europe. EASIN compiles national inventories, DAISIE and CABI rather than measuring, and its pathway assignments carry its own uncertainty flags, which are reported above where it sets them.
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 | Pangasianodon hypophthalmus | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Mekong and Chao Phraya basins, widely farmed and introduced elsewhere | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 100–130 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 15–20 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 22–28 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 6.5–7.5 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 4–20 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 5000 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 460 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum group size | ≥ 4 | 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 2026-08-12. 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. 26 distribution statements held from GBIF checklists — introduced in 19 country. 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 sizeOne sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin
A single source: usgs-nas.
- 130 cm — USGS Nonindigenous Aquatic Species database · Maximum recorded · Observed in the wild · checked 2026-08-29
What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. A documented maximum is held and the catalogue's typical adult range is stated separately, with the relationship between them recorded rather than collapsed. The catalogue's typical adult range already reaches the largest recorded specimen.
What would improve this: Corroborate against a second, independent source.
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.
minimum group sizeAquariumHQ'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: group size — 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: 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.
- Schooling and shoalingThis species is recorded as shoal, and the number it is kept in decides how it behaves.
- Predator and prey sizeIt takes fish that fit in its mouth, and its mouth grows with it.
- Native, introduced and invasiveThis record carries an invasive or legal note, and those are five separate claims that are easy to read as one.
- Scientific and trade namesThis species has been published under more than one accepted name.
- The kinds of water aquarium fish come fromThis record's water bands follow lowland floodplain, which is the kind of water this animal is recorded from.
- How aquarium species get into the wildThis species has a documented introduction outside its native range, with the route recorded.
- Rehoming an animal you can no longer keepThis animal reaches 130 cm. Most of the difficult rehoming cases are fish sold small that were always going to become impossible.
Group size and social behaviour
Shoals in open river channels. Kept alone it is more nervous, and nervousness in a fish this size is how tanks get damaged.