Unlocking the Secrets of Kuhli Loach Keeping

Kuhli loach (lat. Pangio kuhlii) is a fish kind of Cobitidae family. This is a peaceful ground fish that is more active in the evening and at night. This is a bright and easy to keep tank fish. As for its disadvantages, these can be its nocturnal habits and wariness. As a result, you may not see it in a tank during the day. Further in the article, you’ll find out how to keep, feed, breed, and choose tank mates for kuhli loach.

Habitat in the wild

The kuhli loach belongs to the family “Pangio.” The scientific name for this family is “Cobitidae.” Kuhli loaches are part of the genus Pangio, which includes various species of small, eel-like freshwater fish commonly found in Southeast Asia.

The kuhli loach received its specific name from the French ichthyologist Achille Valenciennes by German zoologist Heinrich Kuhl (1797 – 1821). Its initial Latin name was Acanthophthalmus kuhlii, and recently it has been changed to Pangio kuhlii.

Fish habitat is in South-West Asia and India. The fish also inhabits Sumatra, Singapore, Malaysia, Java, and Borneo Islands. In the wild inhabits in slow forest streams with a soft muddy bottom, the stream is usually flowing in the shade of thick tropical flora, where the light doesn’t get through and with a lot of fallen leaves snags in the water.

The presence of driftwood, rocks, and submerged roots in their habitat allows kuhli loaches to find hiding places. They are nocturnal creatures and tend to be more active during the night when they come out to search for food. Their native habitats often feature sandy or muddy substrates with some leaf litter, fallen branches, and plant debris. The kuhli loach is well-adapted to burrow into the substrate, especially during the daytime or when they feel threatened.

Among such a number of covers, loach feels perfect. In the wild, the fish can be seen in small groups; however, it’s not a schooling fish.


The body is pink-yellow with 12-17 wide dark stripes. There are three pairs of barbels (whisker-like) on its head. The dorsal is placed very close to the anal fin. They are almost on the same line.

Kuhli loach, intestinal respiration is peculiar to this loach like other representatives of the family. They can swallow air bubbles that, when getting to some specific areas of their intestinal tract, oxygenate the blood. Also, fishes from the loaches family are known as weather forecasting fishes – they react to atmospheric pressure change and start going crazy, swimming actively along the tank walls or circles.


How big do kuhli loaches get? It is a small loach that will grow to be about 8-12 cm (4-5 in) long, however in a tank, and it won’t be longer than 8 cm. However, it’s essential to note that individual fish can vary in size, and some may be slightly larger or smaller than the average.


How long do kuhli loaches live? Kuhli loach lifespan is about 10 years, although it may be longer. The lifespan of individual loaches can vary within this range, with some living on the shorter end and others reaching the upper end of the spectrum. Several factors influence their lifespan, including water quality, diet, tank conditions, stress levels, and overall care provided by the aquarist.


The coloration of Pangio kuhlii can vary depending on the individual, their mood, and their environment. Typically, Kuhli loaches have a brown or black coloration with lighter bands or stripes running horizontally along their slender body. These stripes help them blend in with their natural habitat and provide camouflage from potential predators.

The color bands are more prominent on the sides of the fish and may appear fainter or broken towards the belly. This color pattern helps them to mimic the dappled light and shadow found in the dimly lit environments they inhabit in the wild.

It’s essential to note that the coloration of Kuhli loaches can change based on their stress levels, health, and mood. When they feel comfortable and safe, they may exhibit more vibrant colors, while stress or illness can cause them to appear paler or duller.


Underneath its eyes, the kuhli loach has a flexible recurved spine that serves as protective means against predators. When trying to catch the loach, these spines strike out and dig into the attacker’s mouth. Usually, this is enough to make it spit out such an unpleasant prey and not to make any further attempts to eat it. These spines produce an illusion of the eye outline’s absence. For this reason, the fish received its name «Acanthophthalmus,» which literally means ‘a torn eye.’

When catching the kuhli loach, don’t forget about its spines underneath the eyes. They can’t do any serious damage, but the prick is quite noticeable. Besides, they hook to the scoop-net with these spines and often get stuck in it.

Catching kuhli loach in a tank is no easy feat. The fish is rather quick, and it’ll use every chance to hide and slip through the net. When taken out of the water, loaches can make funny pulsed squeak sounds.

Albino kuhli loach

The kuhli loach has an albino morph that was bred artificially, and it can’t be seen in the wild. An albino kuhli loach is a variety of the kuhli loach species that exhibits a lack of pigmentation, resulting in a pale or white coloration. Albino kuhli loaches are not a separate species; they are a color morph of the regular kuhli loach.

Since it is a night fish, the species with albino coloring die rather quickly because they are quite noticeable on the bottom.

The characteristics of albino kuhli loaches are generally the same as their regular counterparts, except for their appearance. They have the same slender and elongated body shape, but instead of the typical brown or black coloration with light bands, albino kuhli loaches have a whitish or pinkish hue.

Black Kuhli Loach

The Black Kuhli Loach (Pangio oblonga) is a species of freshwater fish that is closely related to the more commonly known kuhli loach (Pangio kuhlii). Both species are part of the Pangio genus and share similar characteristics and care requirements. However, they are distinct species with slight differences in appearance and behavior.

As the name suggests, the black kuhli loach is characterized by its dark or black coloration. It has a slender and elongated body with subtle lighter bands or markings along its length. The black coloration allows the fish to blend in well with its surroundings in dimly lit environments, providing them with natural camouflage and security.

In terms of care, the black kuhli loach has similar requirements to the regular kuhli loach. They are peaceful, social fish that prefer to live in groups, so it’s best to keep them in a small group of five or more individuals. They are also nocturnal and enjoy exploring and scavenging for food during the night.

To keep black kuhli loaches healthy and happy in an aquarium, it’s important to provide them with a suitable environment that includes hiding spots like driftwood, rocks, and plants. They thrive in a well-maintained tank with proper water parameters, regular water changes, and a varied diet consisting of both animal-based and plant-based foods.

Scientific NamePangio kuhlii
Common NameKuhli loach
Native RegionSoutheast Asia (Malaysia, Indonesia, Thailand, Borneo)
Adult Size3 to 4 inches (7.5 to 10 cm) in length
Lifespan5 to 10 years (in captivity, depending on care)
TemperamentPeaceful and shy
ActivityNocturnal (more active during the night)
Water ParametersSoft to slightly acidic to neutral water (pH 6.0 – 7.5)
Water Temperature24°C to 30°C (75°F to 86°F)
Tank Size20 gallons for a small group
Tank RegionBottom-dwelling, burrows in substrate
DietScavengers – eat small invertebrates, insect larvae, detritus, and microorganisms
CompatibilityPeaceful and best kept in groups
BehaviorShoaling fish – prefer living in groups of five or more
Hiding SpotsRequires hiding places like driftwood, rocks, and plants
Breeding DifficultyModerate, requires specific conditions
Special ConsiderationsSensitive to poor water quality and stress

Difficulties in keeping

Kuhli loach care is simple and easy. What makes the fish different from the others is that it doesn’t have scales, which makes fish very sensitive to medicines, chemical combinations. It has to be considered when treating the fish or putting some chemical products into a tank.

The kuhli loach likes clean and well-aerated water and frequents water renews. It’s necessary to siphonate the bottom while changing the water to remove the litter since loach fish, as a ground one, suffers the most from ammonia and nitrates on the bottom.

Fish is an “owl”; therefore, its activity can be observed during twilights, and at night, it is always hiding. The fish can hardly be seen in the daytime, especially when kept in a tank alone; however, it’s not impossible if one watches the fish for some time. If several fishes are kept in a tank, they become more active at day, maybe due to the appearance of food rivalry.

A group of dozen kuhli loaches will have more active behavior, and it’ll be more close to their behavior in the wild. Nevertheless, fish can also be kept alone in a tank. The fish is rather enduring, and it can live in a tank for quite a long time, and it won’t suffer because of the lack of company.

Care and keeping in a tank

Kuhli loaches are lively and undemanding fish, but their nocturnal habits and absence of scales impose some constraints upon their keeping conditions. It is crucial to provide the fish with clean water and stable water parameters as well as efficient filtration and aeration.

When atmospheric pressure decreases, kuhli loaches become anxious and start swimming in circles in the tank, sometimes jumping out of the water. You’ll need some kind of lid or glass cover for the tank to make sure the fish won’t jump out of the tank.

Tank size

The tank size for kuhli loaches depends on the number of loaches you plan to keep and their tank mates. Kuhli loaches are social and thrive best when kept in groups of five or more individuals. As bottom-dwelling fish, they need enough space to explore, scavenge, and feel secure in their environment.

For a small group of kuhli loaches (5 to 6 individuals), a minimum tank size of 20 gallons (approximately 75 liters) is recommended. This tank size provides enough space for them to roam and interact comfortably. It is ground fish, so not the tank size is determining, but the square of its bottom.

If you plan to keep a larger group of kuhli loaches or have other fish species in the tank, you should consider increasing the tank size accordingly. A larger tank will provide more swimming and hiding space for the loaches and help maintain better water quality in a community setting.

Remember that while kuhli loaches are small, they are active fish, especially during the night. Providing them with enough space and a suitable environment will contribute to their overall well-being and happiness in the aquarium.


The tank should be moderately sized with soft, a little acidic water, and moderately lighted. Since kuhli loaches are nocturnal fish, bright tank lighting will not be appropriate here. They feel more comfortable provided with scattered dim light.

Additionally, it’s essential to provide adequate hiding spots in the form of driftwood, rocks, and plants to create a secure and stress-free environment for the loaches.

Water parameters

As for the tank water composition, kuhli loaches are rather undemanding in this respect. The following water parameters will do:

  1. Temperature: Kuhli loaches prefer relatively warm water. The ideal temperature range is between 24°C to 30°C (75°F to 86°F). It’s essential to keep the temperature stable and avoid rapid fluctuations.
  2. pH Level: Kuhli loaches thrive in slightly acidic to neutral water conditions. The recommended pH range is between 6.0 to 7.5.
  3. Water Hardness: They prefer soft to moderately hard water. The ideal hardness range for Kuhli loaches is around 2 to 12 dKH.
  4. Ammonia and Nitrite: Ammonia and nitrite are toxic to fish. It’s crucial to maintain undetectable levels of these substances in the tank. Regular water testing and appropriate filtration are necessary to achieve this.
  5. Nitrate: Nitrate is a byproduct of the aquarium’s nitrogen cycle and should be kept at low levels. It is less toxic than ammonia and nitrite but can still be harmful in high concentrations. Keeping nitrate levels below 40 ppm is generally recommended.
  6. Water Movement: Kuhli loaches prefer slow-moving or still waters, so it’s best to avoid strong water currents in the aquarium.


Proper filtration is required, and regular water renews (25-30% weekly). Once a week, you should renew the tank water (25-30% of the total tank volume). At that, you should be attentive to make sure that the fish isn’t sucked in by the water flow when siphoning the substrate since the fish can hide in quite unexpected places.

Tank setup: decorations and plants

Several shelters should definitely be in a tank, something like snags or caverns, where the fish will hide during the day. Put several snags with narrow holes or 3-4 ceramic tubes or coconut shells with small holes in them. These will serve as shelters for the fish.

The latter is quite timid. Thus any abrupt movement near the tank makes it hide quickly among thick plants, cracked stones, or snags.

The tank should be thickly planted because the kuhli loach likes spending day time in the plants. The substrate should be small-grained without sharp edges, and sand is an ideal substrate. The fish can dig into the substrate to dig blood worms out of it. If the tank has a sandy bottom, they can dig into the sand completely, which won’t happen in gravel bottom, even with small-grained gravel.

Since the kuhli loach is a bottom dweller, some stones should be quite smooth because their sharp edges and the sheared surface may damage the loach skin.

You should put some grating with small holes on filters input and output to ensure that the fish won’t get inside it. You also should keep in mind some slits in the filter or other holes where the fish can kill itself. Since it’s very curious, it’ll swim everywhere. Though fish spends most of its time on the tank bottom, it’s desirable to cover the tank from the top because the fish can easily get out of it through the tiniest slits.


Kuhli loaches are scavengers in the wild, feeding on small invertebrates, insect larvae, detritus, and microorganisms they find in the substrate and among the plants. Since it is a euryphagous fish, it eats all types of live and frozen feed, different tablets, granules, pellets. The main thing is the feed should fall on the bottom and not being eaten by other fishes.

To ensure that loaches get their food, you should drop it where they prefer staying in the tank, and this should be done shortly before you turn off the lights. This way, you can be sure the fish won’t starve.

Here’s what you can include in their diet:

  1. Live Foods:The kuhli loach likes the following live feed: blood worm, tubifex, brine shrimp, daphnia, etc. Besides, it’s not a problem for kuhli loach if a tubifex or blood worm gets into the substrate because the fish easily finds them and digs them out. The fish is irreplaceable if you feed other fishes with live feed, and some of it falls on a tank bottom and then spoils. However, feeding with live food has several serious dangers in it. You can easily get some infection or invaders into the tank. Many aquarists feed their fish with frozen food, which is much safer than the live one.
  2. Frozen or Freeze-Dried Foods: In addition to live foods, you can also provide freeze-dried or frozen varieties of foods like tubifex worms, daphnia, and brine shrimp.
  3. Vegetables: The fish diet should on 20 % consist of vegetable food. Thus you should additionally feed them with food with high spirulina content. You may use chips, but the most convenient shape, in this case, is pellets that drown. They quickly get to the tank bottom and are available for eating for a long time.
  4. Snails: Also, loaches can feed on snails, but rather seldom. The fish puts its head into the snail’s shell and tries to eat the snail, simultaneously hitting it on the ground to crush the shell.
  5. Commercial Fish Food: High-quality sinking pellets or granules specifically formulated for bottom-dwelling fish are a good staple food. Look for ones that contain a mix of animal and plant proteins to cater to their omnivorous nature.

Tank mates

Kuhli loaches don’t show schooling behavior, but they feel more comfortable in a group of 4-5 or more fishes. If there are 1-2 species in a tank, they behave rather reticent and get out of their covers only at night. The fish is completely peaceful, compatible with any fishes of similar size. They pick up the leftovers that other fishes haven’t eaten from the tank bottom.

They can live together with any small peaceful tank mates dwelling in middle and upper water layers. Here are some compatible tank mates for Kuhli loaches:

However, some fishes are not recommended to put in one tank with loaches. Kuhli loach should be in one tank with cichlids.

First of all, these are large cichlids (oscar fish, green terror, flowerhorn, red terror cichlid). These predators will treat loaches as food. Goldfishes mostly are bottom diggers, and they’ll disturb loaches; besides, they require essentially lower tank water temperature. Territory-dependent bottom-dwelling fish such as red-tailed black sharks also aren’t the best tank mates for loaches, and they may harm them.

Gender differences: male vs female

Gender dimorphism is feebly marked, so without any practical experience, it’s quite challenging to see between the kuhli loach male and female. Unlike some other fish species, kuhli loaches do not have obvious distinguishing features, such as color patterns, fin shapes, or body size, that allow for easy sex identification. In most cases, sexing kuhli loaches requires careful observation of their behavior and physical characteristics over time. However, even with experience, it may still be challenging to determine their sex definitively.

Some general observations that might provide clues to their sex include:

  1. Size and Body Shape: Males are a bit smaller. Their body is narrower, and the abdomen is almost smooth. The adult female’s body is almost cylindrical; their abdomen is a bit rounded, some swelling near its anus can be observed. Females are thicker, which can be noticed from above. If the female has eggs in her, they are seen as elongated greenish spots on her abdomen. However, this difference in size can be subtle and not always reliable.
  2. Behavior: In some cases, females might appear more robust or active during the breeding season, especially if they are carrying eggs.
  3. Vent Position: The male has a pectoral fin whose first ray is thickened and branched. Some experienced aquarists claim that males might have a slightly protruding vent, but this difference can be challenging to spot, especially in smaller and younger individuals.

It’s essential to remember that sexing kuhli loaches accurately may not be crucial for their care and well-being in a home aquarium. As long as they are kept in a suitable environment with proper water conditions and tank mates, they can thrive regardless of their sex.


Breeding kuhli loaches (Pangio kuhlii) in an aquarium can be challenging, as they do not typically breed readily in a home setting. Cases of successful kuhli loach breeding in a tank are rather seldom. Sometimes at good tank conditions, the fish may spawn in a community tank, but the eggs are left unfertilized, and soon they are eaten by the parents or other fishes. However, with proper care and attention to their needs, it is possible to encourage breeding behavior.

In the wild, the kuhli loach spawning period is in December-January. Specialists mention imitation of the rainy season beginning as one of the means to stimulate loaches spawning (it’s desirable to combine it with atmospheric pressure wave).

You should make the tank water softer, decrease its temperature, reduce the lighting intensity and duration. There is no verifiable information if all these factors really work (each by itself or all together).

Generally, in-tank conditions, the kuhli loach spawning is stimulated by injections of gonadotrophin, and spawning starts in 6-8 hours. As a spawning pond, you’ll need a tank of 30 liters capacity (water height 15-20 cm), and a separation net should be put in it.

For spawning, take the fish females with the noticeably rounded abdomen, 2 male fish and 1 female – is the best ratio. The male haunts the female. Then he cuddles his head to hers, and it looks like he is holding her with his pectoral fin.

The kuhli loach couple moves rather fast around the bottom, swimming to the water surface where the female spawns. Small light green eggs stick to the plants’ leaves or fall on the tank bottom. One loach female can lay about 500-700 eggs. The fish parent should be removed from the tank right after spawning.

The incubation time of the eggs lasts about 1 day, then small green ich fry appears. In 4 days, they start swimming and feeding. Loach fish juveniles can be fed with infusorians, rotifers, brine shrimp nauplii, or tubifex cut in small pieces. In a month, striped juveniles become about 1 cm long and become striped. They become reproductive at the age of 8-12 months.