FishfreshwaterModerateHigh invasive risk

Weather loach

A temperate, 25 cm, air-breathing loach that reacts visibly to falling barometric pressure — hence the name. Sold as a tropical community fish, which it is not, and established as a damaging invader in several countries.

Quick profile

Scientific name: Misgurnus anguillicaudatus
Adult size: 20–28 cm (7.9–11 in)
Lifespan: 7–10 years
Temperature: 5–22 °C (41–72 °F)
pH: 6.5–8
Hardness: 5–20 °dGH
Minimum tank: 250 L (66 US gal)
Minimum length: 120 cm
Swimming zone: Bottom
Social: Loose group — at least 3
Diet: Omnivore
Overall confidence: moderate confidence

What keeping this species involves

Extremely hardy, but temperate rather than tropical and much larger than it is sold as.

Muddy-bottomed ponds, paddies and slow rivers; survives in low-oxygen water by gulping air.

Identity and names

Common name: Weather loach
Scientific name: Misgurnus anguillicaudatus
Family: Cobitidae
Order: Cypriniformes
Class: Actinopterygii
Also sold as: dojo loach, pond loach

Adult size and growth

20–28 cm (7.9–11 in)

Typical lifespan in an aquarium: 7–10 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.

Water and tank requirements

A 25 cm bottom-dwelling fish kept in a group, needing floor area rather than depth.

Requirement	Value	Notes
Temperature	5–22 °C (41–72 °F)	Stability matters more than hitting an exact figure.
pH	6.5–8	A stable pH outside the ideal band is usually better than an unstable one inside it.
General hardness	5–20 °dGH	Check your supplier's published figure before choosing species.
Minimum volume	250 L (66 US gal)	A floor, not a recommendation.
Minimum footprint	120 cm long	A 25 cm bottom-dwelling fish kept in a group, needing floor area rather than depth.
Water flow	moderate	Match the outflow to this rather than to the filter's rating.
Lid required	Yes	This species jumps.
Structure	Soft sand deep enough to burrow into, plus cover.

Behaviour

Becomes agitated before weather changes — a genuine and well-documented response to pressure.
Gulps air at the surface and absorbs oxygen through the gut.
Escapes through the smallest gap.

Feeding

Diet type: Omnivore
Staples: Sinking pellets, Frozen bloodworm, Blanched vegetables, Snails

Breeding

Strategy: Seasonal egg-scattering
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.

Risk this species poses to common tankmates
Towards	Risk	What it means
Small fish	none	Anything that fits in the mouth is at risk once this species reaches adult size.
Adult dwarf shrimp	moderate	Cover reduces losses but rarely prevents them where the risk is high.
Shrimplets	high	Determines whether a shrimp colony can grow rather than merely persist.
Snails	high	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.

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.

Best kept in an unheated tank or an outdoor pond in a temperate climate.
Listed as an invasive species in several countries; never release.

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: East Asia — China, Korea, Japan, Russia; widely introduced elsewhere
Habitat: Muddy-bottomed ponds, paddies and slow rivers; survives in low-oxygen water by gulping air.

What the checklists say

38 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	26	A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal.
Recorded as invasive	1	A checklist states the species is invasive here. AquariumHQ reproduces that assessment; it does not make one.
Recorded as present, establishment means not stated	11	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

Established as an introduced species in parts of North America, Europe and Australia, where it displaces native bottom-dwellers. Sale or possession is restricted in several jurisdictions. Check the position locally before acquiring, and never release.

What AquariumHQ has recorded, by jurisdiction, with the instrument each entry comes from and how far the check went. Ecological risk and legal status are separate: a species can be ecologically risky and legally unrestricted, or restricted where it could never establish.

GB

Prohibitedrelease

A temperate-tolerant species capable of surviving British winters, which makes it one of the aquarium fish of most concern for establishment. Release is an offence and the risk here is not theoretical.

Instrument: Wildlife and Countryside Act 1981, section 14; the species is monitored by the GB Non-native Species Secretariat

Instrument recorded, species entry not re-checked · last checked 2026-08-11 · AquariumHQ has recorded the instrument and what it does, but has not re-confirmed this species' entry against the current consolidated text. Listings are amended, so treat this as a pointer to the right law rather than as a confirmation of the current position, and check with the authority before acting.

US

Restrictedpossession

Established non-native populations are recorded in several US states, and a number of states list the species as prohibited or restricted. There is no single federal position.

Instrument: State-level prohibited and restricted species lists, which vary by state

This is a species where the answer genuinely depends on the state, and a national answer would be misleading in both directions.

AU

Prohibitedimport

A cold-tolerant loach with a documented capacity to establish is not a species Australia's permitted-list regime admits.

Instrument: Environment Protection and Biodiversity Conservation Act 1999 — List of Specimens taken to be Suitable for Live Import

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	Misgurnus anguillicaudatus	Observed / measured	high confidence	Catalogue of Life; GBIF — Global Biodiversity Information Facility
native range	East Asia — China, Korea, Japan, Russia; widely introduced elsewhere	Observed / measured	moderate confidence	GBIF — Global Biodiversity Information Facility
adult size	20–28 cm	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
lifespan	7–10 years	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
temperature	5–22 °C	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
ph	6.5–8 pH	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
general hardness	5–20 °dGH	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
minimum tank volume	≥ 250 L	AquariumHQ editorial position	moderate confidence	AquariumHQ husbandry synthesis
minimum tank length	≥ 120 cm	AquariumHQ editorial position	moderate confidence	AquariumHQ husbandry synthesis
minimum group size	≥ 3	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.