Gold Weather Loach (Misgurnus anguillicaudatus)

Choose a Gold Weather Loach for a large, cool indoor aquarium

The Gold Weather Loach is a golden ornamental strain of Misgurnus anguillicaudatus, the loach known in Europe as the weather loach, in the United States as the dojo loach and in FishBase as the pond loach. Seriously Fish calls the species the oriental weather loach and notes that xanthic, or golden, strains are available with exactly the same care as the wild, speckled form. It is a long, slim, peaceful bottom-dweller with whisker-like barbels around the mouth, and it spends much of its time digging in soft sand or lying with only its head showing.

The species is native to Siberia, Sakhalin, Korea, Japan and China south to northern Vietnam. It lives in shallow, slow rivers and streams, swamps, oxbows, backwaters and paddy fields, usually heavily vegetated with soft mud or silt. When the water runs short of oxygen it gulps air at the surface and absorbs oxygen through its gut and skin. OATA explains the name: weather loaches become restless when the air pressure drops, as it does before a change in the weather.

Decide from the complete care picture

The gallery images are representative, prepared from a reference photograph, and do not show the exact fish supplied; golden strains vary from pale yellow to deep orange.

Keep it indoors: the law and the wild

This is an aquarium fish only. In England and Wales the government's ILFA aquarium ornamentals checklist lists Misgurnus anguillicaudatus among the freshwater fish that may be kept under a general licence in indoor aquaria only, so a garden pond is not allowed. Seriously Fish also says the species should never be kept outdoors.

The reason is its record in the wild. Seriously Fish lists introduced populations in Germany, Spain, Italy, Kazakhstan, Uzbekistan, Turkmenistan, the Philippines, the USA including Hawaii, Canada and Australia, spread mainly through the aquarium trade. It points to the fish's high breeding potential and low vulnerability to predators as conservation concerns, while noting there is no proof yet of harm to native fish. FishBase goes further: at least one country reports adverse ecological effects, and it lists the species as a potential pest.

Plan for the fish's whole life

• Never release it: OATA states that aquarium animals and plants must never be released into the wild; doing so is illegal and usually harms the fish and native wildlife.
• Dispose of water and waste carefully: OATA advises disposing of old water, substrate and decorations so that nothing reaches a natural watercourse.
• Rehome, do not release: if you can no longer keep it, contact us or a local aquatic shop or club to find it a new indoor home.

Select the size and plan the group

One purchase quantity supplies one live Gold Weather Loach, medium-large size. Sex is not specified. Seriously Fish notes that females are heavier-bodied and slightly larger, while mature males develop enlarged pectoral fins with a thickened second ray and swellings behind the dorsal fin that are visible from above. OATA adds that sexing is difficult unless the fish are breeding.

OATA describes weather loaches as social fish and recommends a group of at least three or four, as smaller groups can cause stress. Seriously Fish says a single fish can live alone but is more at ease and more active with others of its kind.

Work from the group you intend to keep

• One fish: best as an addition to an existing group.
• Three or four fish: the group OATA recommends.
• Larger groups: only in an aquarium big enough for every adult.

Check our current delivery and Live Arrival Guarantee policy before ordering.

Plan the aquarium around a 25–28 cm adult

Seriously Fish and FishBase give a maximum of 28 cm standard length; OATA says up to 25 cm. OATA also reports lifespans of up to 10 years, so this is a long-term fish. The sources disagree on space: OATA suggests at least 120 litres for a group of three or four, while Seriously Fish gives a minimum base of 120 × 45 cm, about 243 litres. Use the larger figure, because a group of long fish needs floor area to dig and rest.

Use a three-step space check

1. Measure the base: at least 120 cm long and 45 cm front to back.
2. Count adult bodies: three or four loaches of up to 28 cm plus every other fish at its adult size.
3. Check the room: a spot away from draughts, radiators, direct sunlight, noise and vibration, as OATA advises.

Lay soft sand and secure every stone

Weather loaches often bury themselves, so Seriously Fish recommends a soft, sandy or fine gravel substrate, and OATA advises sand or smooth gravel to protect their skin. Place water-worn rocks and driftwood on the glass before adding the sand, so that digging cannot topple them. Lighting can be dim unless you grow plants, and leaf litter makes a natural addition. OATA suggests live plants for cover, or plastic plants and ornaments such as pots and caves, avoiding anything with rough or sharp edges.

Fit a tight lid, because weather loaches jump, and cover the filter intake so that a small fish cannot be drawn in. Seriously Fish also advises against adding them to a biologically immature aquarium.

Divide the footprint by function

Keep the water cool, clean and stable

This is not a tropical fish. Seriously Fish gives 18–23°C and notes that it tolerates about 5–25°C; FishBase gives 5–25°C. OATA gives 18–24°C and says no heater is needed if the house is centrally heated and the room does not drop below that range. Keep temperature swings small, and keep the tank out of direct sun so that it does not overheat in summer.

Many UK tap waters fall inside this pH and hardness range, but check your water company's figures or use our water matcher before you buy.

Separate habitat values from waste readings

These limits come from OATA's weather loach care sheet. Our nitrogen cycle guide explains why a new tank must be matured before any fish go in.

Filter well but keep the flow gentle

OATA treats a filter as essential. Seriously Fish recommends low flow with moderate oxygenation; for a 243 litre aquarium its equipment guide works out a filter rated about 970–1,215 litres per hour, four to five turnovers per hour. Spread the outflow so that the bottom stays calm, and keep some surface movement for oxygen.

Follow a weekly maintenance sequence

1. Test ammonia, nitrite, nitrate, pH and hardness weekly, as OATA advises.
2. Change 25% of the water at least once a week, siphoning waste from the sand surface.
3. Treat new water with a tap water conditioner and match its temperature.
4. Rinse filter media in removed tank water, never under the tap.
5. Rake the top of the sand lightly if it compacts, keeping clear of buried loaches.

Feed sinking foods and small live or frozen extras

In the wild it mainly hunts insect larvae and small crustaceans. OATA describes weather loaches as omnivores that accept most foods: offer a good-quality sinking catfish pellet with small live or frozen foods such as Daphnia, bloodworm and brine shrimp (Artemia). Seriously Fish recommends a varied diet with regular live or frozen foods, not dried food alone.

Build one measured meal

• Make it sink: drop pellets where the loaches forage, not where the goldfish feed.
• Feed once a day: OATA advises offering only what is eaten within a few minutes.
• Add variety: rotate frozen and live foods through the week.
• Remove leftovers: food buried in sand fouls the water.

Introduce it to a mature aquarium

Confirm a mature filter, zero ammonia and nitrite, and water at 18–23°C before the fish arrives. Use OATA's floating bag method: switch off the lights, float the bag for about 10 minutes, add small amounts of tank water over up to 20 minutes, then release the loach and keep the bag water out of the tank. Our acclimatisation guide walks through it.

Use a first-week checkpoint plan

A new loach often buries itself for the first days. That is normal; check that it comes out to feed.

Watch for weather and health changes

Restless swimming when the air pressure falls is normal for this fish. Frequent trips to gulp air are different: the species does this in the wild when the water is short of oxygen, so check aeration and water quality.

Pair each observation with an action

Record readings and observations before treating anything, and contact us with them if a problem continues.

Choose calm tank mates that use the upper water

Seriously Fish describes Misgurnus as peaceful with each other and with other fish, but they may eat eggs, fry or very small fish. They do best with medium to large, active fish that live higher in the water, and they may disturb slow fancy goldfish, especially at feeding time. OATA says weather loaches do well with most fish in unheated aquariums.

Decide from the suits and avoid list

From our range, consider the Bronzed Comet Goldfish and the Wakin Goldfish; our comet goldfish guide covers their own needs. For another cool-water loach, compare the Stone Loach. Browse more in our loaches and oddball fish, the loaches and algae eaters category, our goldfish and coldwater fish, other coldwater fish and our coldwater fish buying guide, and check any mix with our tank mates tool.

Know what breeding involves

Captive breeding reports are scarce, and Seriously Fish says fish in the trade are probably spawned with hormones. By comparison with its European relative M. fossilis, spawning probably starts at two to three years and about 110 mm standard length; the female leads the male into dense plants, where he wraps around her as the eggs are released. The fry have external gill filaments that disappear after 10–12 days. On Hokkaido in Japan, an all-female population reproduces by sperm-dependent gynogenesis, needing sperm from a related species to start the eggs developing.

Answer Gold Weather Loach buying questions

Is the Gold Weather Loach the same fish as the Dojo Loach?

Yes. It is a golden ornamental strain of Misgurnus anguillicaudatus, known as the oriental weather loach, the dojo loach and, in FishBase, the pond loach. Seriously Fish says the golden form needs the same care as the wild form.

Can I keep a weather loach in my garden pond?

No. In England and Wales it is on the government list of fish that may be kept under a general licence in indoor aquariums only, and Seriously Fish says it should never be kept outdoors. It has become established in the wild in several countries.

Does a weather loach need a heater?

Usually not in a centrally heated home. Seriously Fish gives 18–23°C and OATA 18–24°C, and OATA says no heater is needed if the room does not fall below that range.

How big do weather loaches get?

Seriously Fish and FishBase give up to 28 cm standard length, while OATA says up to 25 cm. Plan for a long, slim fish of 25–28 cm.

What size aquarium does it need?

Seriously Fish gives a minimum base of 120 × 45 cm, about 243 litres, and OATA at least 120 litres for a group of three or four. Use the larger footprint for long-term care.

How many should I keep?

OATA recommends a group of at least three or four. Seriously Fish says one can live alone but is more at ease and active with others of its kind.

Can it live with goldfish?

Yes, with active goldfish such as comets that swim higher in the water. Seriously Fish warns that it may disturb slow fancy goldfish at feeding time, and it may eat eggs, fry or very small fish.

Why is it called a weather loach?

It becomes restless when the air pressure falls, as it does before a change in the weather. The behaviour is normal and not a sign of illness.

Consult the care references

• Seriously Fish: Misgurnus anguillicaudatus: names, range, habitat, size, aquarium base, set-up, water values, diet, behaviour, sex differences, breeding, golden strains and introduced populations.
• FishBase: Misgurnus anguillicaudatus: recorded length, temperature range, distribution, introductions and pest status.
• OATA: How to look after hillstream and weather loaches: UK guidance on temperature, tank size, group size, set-up, feeding, maintenance and never releasing fish.
• GOV.UK: Introduce or keep non-native fish and shellfish: the licensing rules for non-native fish in England and Wales.
• GOV.UK: ILFA aquarium ornamentals checklist: genera and species that may be kept in indoor aquaria only.
• Tropical Fish Co delivery policy: current dispatch and Live Arrival Guarantee terms.