Eel Kuhli Loach (Pangio sp.)

Eel Kuhli Loach at a glance

The Eel Kuhli Loach is a slender, eel-shaped loach from the genus Pangio, a group of peaceful bottom-dwellers that spend much of their lives burrowing in soft sand. Each purchase is one live fish. These are group fish for a calm, well-covered aquarium: plan for at least five or six together, give them soft sand to dig in, and choose small, peaceful companions.

The name needs a word of explanation. You may see this fish labelled Pangio kuhlii anguillaris, a label that joins two separate species names, Pangio kuhlii and Pangio anguillaris. Seriously Fish notes that a handful of Pangio species are traded under the generic name eel loach, and that Pangio anguillaris belongs to a group of closely related species told apart by details such as vertebra counts, barbels and cheek scales rather than at a glance. The genus itself is certain: WoRMS lists Pangio as an accepted genus in the family Cobitidae. The exact species has not been identified, so the care advice here follows the genus Pangio and its care group.

In practice that means two kinds of guidance on this page. Advice written for loaches as a group comes from the OATA care sheet. Where a single-species figure helps with planning, it comes from the FishBase and Seriously Fish profiles for Pangio anguillaris, one of the species sold as eel loaches, and it is named as such each time.

The good news for buyers is that the uncertainty affects less than you might think. The loach care sheet and the Pangio anguillaris profile agree on the essentials: keep a group rather than a single fish, provide a sand substrate and give plenty of shelter. What the species name would mainly settle is the adult size and the finer details of colour and pattern.

Is this loach right for you?

Key facts

What arrives and what to expect

Each fish is supplied at a dispatch size of about 6–7 cm. That is the size at dispatch, not the adult size, and because adult length depends on the exact species, plan the aquarium with room for your loaches to keep growing.

Expect these fish to keep a low profile. FishBase describes Pangio anguillaris spending much of its time buried in the sand or slowly foraging across its surface, and Seriously Fish notes that eel loaches will often pack themselves into a single nook, cranny or cave when at rest. A group that has vanished into the sand is behaving normally; the reward is watching them emerge and sift through the substrate together.

Sex is guaranteed only when the selected option explicitly states male or female. This Eel Kuhli Loach listing has no sex-guaranteed option. Seriously Fish describes some differences between adult males and females in Pangio anguillaris, covered in the breeding notes below, but they apply to adults of that one species.

Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals. Seriously Fish also records that wild populations of Pangio anguillaris differ in colour pattern, some with a stronger stripe along the side and others with fine dark spots, so the fish you receive may not match the photograph exactly.

Where eel loaches come from

Knowing where eel loaches live explains most of what they need. FishBase records Pangio anguillaris in medium to large rivers across the Mekong and Chao Phraya basins, the Malay Peninsula, Sumatra and Borneo. It lives near the bottom over sand or silt, among debris and decaying vegetation in stretches with slow current, and spends much of its time buried in the sand.

• Bottom-dwelling: FishBase classes the species as demersal, living on or near the bottom.
• Diet in the wild: mostly benthic invertebrates, the small animals living in and on the bottom.
• Air-breathing: FishBase notes facultative air-breathing in the genus, meaning these fish can take air as well as breathing through their gills.
• Breeding habitat: very shallow water with a lot of vegetation, most commonly in flooded forests or grasslands along the water's edge.
• Conservation: Pangio anguillaris is assessed as Least Concern on the IUCN Red List.

Seriously Fish adds that Pangio anguillaris is most commonly available as bycatch among shipments of other fishes.

What that means in your aquarium

Setting up a sand-bottomed aquarium

OATA's general rule for loaches is to buy an aquarium as large as is reasonable, and ideally one that can hold at least a small shoal. It recommends an aquarium of at least 80 litres for a shoal of the smallest loach species. Seriously Fish suggests a base of at least 60 × 30 cm, or equivalent, for Pangio anguillaris. For a group of five or six eel loaches, treat 80 litres as the sensible starting point and favour floor space over height, since these fish live on the bottom.

Substrate: soft sand is essential

Seriously Fish is clear that eel loaches need a soft, sandy substrate, because they like to dig and spend some of their time completely buried. On coarser gravel they may become stressed or damage themselves, and their feeding can be inhibited. OATA makes the same point for loaches in general: fine gravel or, ideally, sand protects their sensitive skin and barbels when they bury themselves.

Furnishing for shade and cover

• A few driftwood roots and branches placed to create plenty of shady spots.
• Dried leaf litter for extra cover and a more natural feel.
• Fairly dim lighting, which Seriously Fish describes as preferable.
• Plants such as Microsorum, Taxiphyllum and Cryptocoryne species.
• If you do not use live plants, OATA suggests plastic plants and suitable ornaments such as plant pots or model caves for shelter.

Filtration, flow and escape-proofing

A filter is essential in every aquarium. The RSPCA explains why: fish release ammonia, and a working biological filter lets beneficial bacteria convert it first into nitrite and then into the safer nitrate. For eel loaches, Seriously Fish recommends gentle filtration with a little surface agitation, and advises avoiding high flow rates.

Two practical details matter more with these fish than with most. First, make sure small specimens cannot enter the filter intakes. Second, cover the aquarium well, because Seriously Fish notes that most loaches jump at times, especially when introduced to a new environment. Check for gaps around the lid, cable cut-outs and pipework before the fish arrive.

Laying out the tank for a group

Leave open stretches of sand for foraging and put the cover, such as wood, leaf litter and planted areas, around them. Because eel loaches often rest together in one spot, a few generous shared hiding places close to the sand suit them well. A layout like this also lets you see the group when it comes out to feed.

The filter must be fully matured before any fish go in. Our guide to setting up and maturing a tropical tank walks through that process step by step.

Water conditions

Because the species is unconfirmed, the water targets on this page combine two sources. The OATA care sheet for loaches gives broad guidance for the group, and the Seriously Fish profile gives aquarium ranges for Pangio anguillaris. The targets below sit where the two agree.

For reference, OATA's full loach guidance is 22–27 °C, pH 6.5–8.0, general hardness of 4–12 °dH and carbonate hardness of 3–10 °dKH. That is broad guidance for many loaches at once rather than a species-specific optimum. Seriously Fish gives 22–29 °C, pH 6.0–7.5 and 0–8 dGH for Pangio anguillaris in the aquarium.

The wild picture is more acidic still. FishBase records the habitat of Pangio anguillaris at 24–26 °C, pH 5.0–6.0 and 5–12 dH. Those are wild river figures rather than aquarium targets, but they point towards soft to moderately hard water rather than very hard, alkaline conditions.

Testing and stability

Test your tap water before you buy, so that you know where it sits against these ranges. Our guide to aquarium water parameters explains what each test measures and why it matters, and the water parameter matcher lets you compare your own readings with the targets above. Whatever your water, stability matters more than chasing an exact number: keep ammonia and nitrite at zero, stop nitrate building up, and make any change gradually.

If your tap water is hard

If your tap water sits well above these ranges, decide how you will bring it down before the fish arrive, and prepare every batch of replacement water the same way, so that the aquarium does not swing between soft and hard water from one change to the next.

Feeding a sand-sifting loach

Eel loaches feed from the bottom. Seriously Fish describes Pangio anguillaris as chiefly a micropredator that sifts mouthfuls of substrate through its mouth and gills, extracting insect larvae, small crustaceans and similar food, with some organic detritus and plant material also taken in. FishBase records its wild diet as mostly benthic invertebrates.

A practical menu

• Good-quality sinking pellets or granules as the everyday base, as OATA recommends for loaches.
• Regular meals of live or frozen foods: Seriously Fish lists Daphnia, Artemia, bloodworm, micro worm and grindal worm.
• Freeze-dried bloodworm and freeze-dried Artemia as convenient extras.
• Small items such as daphnia, small bloodworm or tubifex, which OATA notes loaches benefit from.

How much and how often

OATA's guidance for loaches is to feed only what they can eat within a few minutes, once a day. Take care not to overfeed: uneaten food breaks down and releases toxic waste into the water. Because eel loaches forage on and in the sand, make sure the food actually sinks to where they are, and remove any leftovers once they have finished.

Vary the menu across the week rather than relying on one food. Seriously Fish recommends regular meals of live and frozen foods alongside dried food, which is closer to their natural diet of small invertebrates.

In a community aquarium, keep an eye on whether the loaches are getting their share. Sinking foods placed where the group emerges help them get a share before faster fish take everything from the upper water.

Routine care and health

Loaches reward a steady routine. The OATA care sheet recommends:

• A partial water change of 25% at least once every week, using a siphon to remove solid waste.
• Testing the water at least once per week, so that ammonia and nitrite never build up.
• Treating replacement water with a tap water conditioner to remove any chlorine or chloramine.
• Checking filters for blockages and, when the media needs cleaning, rinsing it lightly in tank water removed during a water change. Do not run it under the tap, because chlorine or chloramine may kill the beneficial bacteria.

When siphoning a sand bed, work gently over the surface so that you lift waste without disturbing buried loaches. OATA adds that good husbandry is essential because loaches can be stressed by even the smallest amounts of ammonia.

Handling and medication

OATA notes two features of loaches that call for care. They have a spine just underneath each eye, so handle them carefully. They also have reduced or absent scales, so they may be intolerant of some medications; check that any treatment is suitable for scaleless or loach species before you use it.

Signs worth acting on

Because eel loaches are often hidden, it helps to see them at feeding time and take a quick look at each fish. OATA lists these changes to watch for:

• Swimming: hanging at the surface, sitting on the bottom or swimming erratically.
• Colour: turning darker or paler than normal.
• Temperament: hiding more than normal or a change in aggression.
• Breathing: gill covers moving faster or slower than normal.
• Appearance: white spots, fluffy growths, or lost fins or scales.
• Condition and feeding: weight loss or gain, eating less or losing interest in food.

If you are concerned, test your water quality first, as OATA advises, and get in touch with us if you would like guidance.

Keep a simple log of test results, water changes and how many loaches you counted at feeding time. With fish that spend so much time out of sight, a regular head count is the easiest way to notice if one is missing, unwell or has found its way out of the tank.

Before you order: a checklist

Most problems with eel loaches can be prevented before the fish are ordered. Work through this list first:

• Aquarium: at least 80 litres for a group of five or six, with generous floor space.
• Substrate: soft sand, never coarse gravel.
• Cover: a tight-fitting lid, with gaps around cables and pipework closed off.
• Filter: fully matured, gentle in flow, with intakes guarded so small fish cannot enter them.
• Water: tested and holding steady within 22–27 °C, pH 6.5–7.5 and 4–8 dGH, with ammonia and nitrite at zero.
• Furnishings: driftwood, leaf litter, plants or ornaments for shade and shared hiding places.
• Food: sinking pellets or granules, plus live or frozen small foods such as daphnia or bloodworm.
• Companions: small, peaceful fish only, with aggressive loaches ruled out.
• Group: enough eel loaches bought together to make a group of at least five or six.

It also helps to check any treatments you keep in the cupboard. OATA notes that loaches may be intolerant of some medications, so know in advance which products are unsuitable for scaleless fish.

Arrival and the first days

We hand-bag fish in pure oxygen and pack them in an insulated poly box, with a heat pack when the weather calls for it. A licensed live-animal courier carries the parcel on a tracked service, and we email you the tracking number and your confirmed delivery date so that you know when to be in. The full conditions are on our delivery and Live Arrival Guarantee page.

1. Be at the delivery address to receive the parcel. Live fish cannot be left unattended, and the guarantee requires someone to be there to receive them.
2. On the day the parcel arrives, film one continuous unboxing video: the parcel still sealed with the outer box visible, then you opening it, then the fish still inside the sealed bag.
3. Float the bag for 20–30 minutes before releasing the fish.
4. Release the fish into the aquarium without pouring the bag water into your tank.
5. If anything has gone wrong, contact us the same day with your order number and the unboxing video. WhatsApp is fastest, and we will arrange a replacement or refund.

The first days

Before any fish go in, OATA advises checking that the aquarium is the right size for the number of loaches you plan to keep and that ammonia and nitrite both read zero. It also warns that adding too many fish too quickly can cause new tank syndrome, when there are not enough nitrifying bacteria to cope with the extra waste, so build up the rest of the community gradually.

Put the cover back on as soon as the fish are released. Seriously Fish notes that loaches are especially likely to jump when introduced to a new environment. Eel loaches often head for the sand or a shared hiding place, so do not be alarmed if you see little of them at first; check on them at feeding time instead.

Healthy fish, OATA notes, have clear bright eyes, undamaged fins and intact scales, with no ulcers or bumps.

Breeding and sexing

Eel loaches are not a fish to buy with breeding in mind. Seriously Fish states that Pangio anguillaris has not been bred in captivity as far as it knows, and cites Rainboth (1996) for spawning in shallow water with abundant vegetation. FishBase describes the species breeding in very shallow water with a lot of vegetation, most commonly in flooded forests or grasslands along the water's edge. There is no dependable home-breeding method to follow, so buy these fish to enjoy as a group rather than as a breeding project.

Telling males from females

For Pangio anguillaris, Seriously Fish describes adult females as typically heavier-bodied and a little larger than males. In adult males, the first ray of the pectoral fin is branched and thickened, and the pectoral fins are upturned and longer than those of females. Mature males of some populations develop what appears to be a hump on the head. These describe adults of Pangio anguillaris, so treat them as a rough guide at best for fish whose species is unconfirmed.

Keeping eel loaches as a group

Seriously Fish describes Pangio species as peaceful both with one another and with other fishes, and knows of no reports of them harming tank mates, although they may prey on eggs or fry. In nature they are often found in large aggregations, and in the aquarium they will often pack themselves into a single nook, cranny or cave when at rest. For that reason, Seriously Fish recommends a group of at least 5–6 as the minimum purchase.

OATA reaches the same number for loaches as a group: keep them in groups of at least five in the home aquarium, and more is better.

• Buy the whole group together so the fish settle as one.
• Keep at least five or six, and more if the aquarium allows.
• Provide several shared hiding places, since the group often rests in one spot.

Choosing tank mates

The best companions are small, peaceful fish from similar environments. Seriously Fish names genera such as Boraras, Sundadanio, smaller Rasbora, Trichopsis, Sphaerichthys and Kottelatlimia as the best tank mates for eel loaches. Some sand-dwelling loaches from the family Nemacheilidae are also suitable, but research each species properly first, as some can be excessively territorial, aggressive or competitive.

The OATA loach care sheet covers loaches as a whole. It notes that loaches are compatible with most community fish, that loaches may be too active for some shy species, and that some species, such as the red-tailed botia and the skunk loach, can be quite aggressive and should only be mixed with larger, more robust fish. A small, peaceful eel loach is not a robust companion for those species. For Pangio in particular, Seriously Fish's list of small, peaceful fish from similar habitats is the better guide.

If you are planning a wider loach community, browse our loaches and oddballs range with care. It covers species with very different adult sizes and temperaments, and OATA notes that the clown loach, for example, can grow to over 30 cm and needs a large aquarium from the outset.

Planning the whole community

Choose companions that share the same water. Many of the small fish Seriously Fish recommends come from similar environments, so a community built around them can be kept at one steady set of values instead of a compromise that suits nobody. Add fish gradually, as OATA advises, so that the filter bacteria can keep pace with each increase in stocking and feeding. Eel loaches are easy to overlook once they have buried themselves, so count them into the stocking level of the tank from the start.

Eggs and fry

Because eel loaches may prey on eggs or fry, a community in which other fish are breeding needs a separate plan for any young you want to raise.

Common questions

How big does an Eel Kuhli Loach grow?

Adult size depends on the exact species, and this fish has been identified to the genus Pangio rather than to species. Eel loaches are long, slender fish, so choose an aquarium with room for growth beyond the size at dispatch.

What size aquarium does an Eel Kuhli Loach need?

OATA recommends an aquarium of at least 80 litres for a shoal of the smallest loach species, and Seriously Fish suggests a base of at least 60 × 30 cm for Pangio anguillaris. Choose generous floor space and a well-fitting cover, because loaches jump at times.

How many should I keep together?

Keep at least five or six. Seriously Fish says Pangio species are often found in large aggregations in nature and recommends 5–6 as the minimum group, and OATA advises groups of at least five for loaches, adding that more is better.

Is an Eel Kuhli Loach a good fish for beginners?

It suits a patient keeper with a mature, stable aquarium. OATA describes loaches as usually easy-going and undemanding of water chemistry, but these fish still need soft sand, a secure cover, a group of at least five and consistently clean water.

What does it eat?

Seriously Fish describes Pangio anguillaris as a micropredator that sifts sand for insect larvae and small crustaceans. Offer good-quality sinking pellets or granules with regular meals of live or frozen daphnia, Artemia, bloodworm, micro worm or grindal worm, feeding only what the fish can eat within a few minutes, once a day.

What temperature and pH does an Eel Kuhli Loach need?

Aim for 22–27 °C, pH 6.5–7.5 and 4–8 dGH. That is broad OATA loach guidance, narrowed to where it overlaps the Seriously Fish profile for Pangio anguillaris, because the exact species is unconfirmed. Keep conditions stable.

Is it aggressive, or does it nip fins?

No. Seriously Fish describes Pangio species as peaceful both with one another and with other fishes, with no reports of them harming tank mates, although they may prey on eggs or fry.

Which fish can live with an Eel Kuhli Loach?

Choose small, peaceful fish from similar habitats. Seriously Fish names genera such as Boraras, Sundadanio, smaller Rasbora, Trichopsis, Sphaerichthys and Kottelatlimia. Some sand-dwelling Nemacheilidae loaches can also work, but research each one, and avoid aggressive loaches such as the red-tailed botia or skunk loach.

How does a live fish arrive safely in the UK?

We hand-bag fish in pure oxygen inside an insulated poly box and send them with a licensed live-animal courier on a tracked service. Be in to receive the parcel, film one continuous unboxing video from the sealed parcel to the fish still in the bag, then float the bag for 20–30 minutes before releasing the fish without the bag water.

Sources and further reading

• WoRMS: Pangio. Accepted genus and family placement.
• FishBase: Pangio anguillaris species summary. Wild habitat values, distribution, biology notes and IUCN status for one species sold as an eel loach.
• Seriously Fish: Pangio anguillaris profile. Aquarium size, water, set-up, diet, behaviour, tank mates, sexing and the eel-loach trade name.
• OATA: how to look after loaches. Group-level care for loaches, covering water, aquarium set-up, introduction, maintenance, health checks, feeding and compatibility.
• RSPCA: fish environment. General welfare guidance on filtration and the nitrogen cycle.
• Tropical Fish Co delivery and Live Arrival Guarantee page, linked in the arrival section above. Packing, courier and claim conditions.