The coolie loach is a bottom-dwelling fish that likes digging in the sand and investigating every hidden spot in your aquarium. Despite their eel-like appearance and unique burrowing behaviors, these fish are surprisingly gregarious and prefer to be in the company of their own kind. In nature and in the home aquarium, the coolie loach is most active around dusk and at night, while keeping concealed throughout the day. Although there are several subspecies of this fish, they all have the same nutritional and ecological requirements, therefore identifying the precise subspecies isn't necessary.
Common Names: Kuhli loach, coolie loach, khuli loach, prickly eye
Scientific Name: Pangio kuhlii
Adult Size: 4 inches
Life Expectancy: 10 years
|Minimum Tank Size||15 gallons|
|Diet||Omnivore, enjoys live foods|
|pH||6.0 to 6.5|
|Hardness||up to 10 dGH|
|Temperature||75 to 86 degrees F (24 to 30 degrees C)|
Origin and Distribution
The coolie loach is native to Southeast Asian streams, including those in Borneo, Java, western Malaysia, Singapore, Sumatra, and Thailand. Pangio kuhlii is the current scientific name for this fish, which was previously known as Cobitis kuhlii and then Acanthophthalmus kuhlii. Former scientific names are still used in many references.
Pangio kuhlii is one of two dozen kuhlis species, many of which are quite similar to one another. Based on variations in coloring and patterns, the subspecies Pangio kuhlii sumatranus and Pangio kuhlii myersi were named. Pangio kuhlii has fewer and darker bands than P. sumatuanus (also known as the Sumatra Kuhli). The Pangio kuhlii myersi has even larger bands. Although Pangio kuhlii is the most popular and widely accessible coolie loach, it is not uncommon to buy a wrongly called coolie loach.
Colors and Markings
Coolie loaches have an eel-like body with several dark brown bands or stripes that partially or completely ring the whole body. Subspecies have different color patterns on their bodies and stripes. The dorsal fin of the coolie loach is positioned in the lowest third of the body, considerably closer to the tail than the head, and the fins are small.
A tiny layer of translucent skin covers the coolie's eye, which is buried under one of the black bands. A pair of strong spines behind the eyes raise when the fish is threatened, making it tough for a predator to devour them or for an owner to net them; use caution when doing so. The coolie loach's mouth is ringed by four pairs of barbels and tips downward.
Coolie loaches thrive in groups of at least a half-dozen other coolies, and they get along well with non-aggressive fish. They are shy when kept alone and will hide the most of the time. Keep coolies with little fish such as danios, rasboras, and instead of huge or territorial fish like cichlids.
Coolie Loach Habitat and Care
The coolie loach prefers to reside in areas with clear, slow-moving water washing over sand. They can handle a wide range of water conditions, but prefer slightly acidic water with temperatures in the mid-70s Fahrenheit. These obligate burrowers will be damaged by sharp edges on the substrate, thus it must be smooth. These fish use sand as their preferred substrate.
Coolie loaches will jump out of the tank if startled, so make sure the tank is well covered. Because there have been several reported occurrences of loaches swimming up the entrance tube and becoming stuck in the filter, the inlet tube of the filter should also be covered with mesh or a sponge. Coolie loaches have gone missing for months, only to be discovered alive beneath the UGF or within a canister filter. Make a tally of your coolies to make sure you haven't forgotten about any, or the fish will suffer and starve.
When feasible, coolie tanks should have plenty of secure hiding places, ideally under low, living plants. Coolie loaches prefer rocks, driftwood, and caves as decorations. Keep the illumination low, however a well-lit tank can be used if it is extensively vegetated, providing shaded spots for the loaches to hide. Install a moonlight in the tank to view their nighttime activity.
Coolie Loach Diet and Feeding
The preferred diet of coolie loaches is live foods. They will, however, eat a wide range of meals, including frozen, freeze-dried, tablets, wafers, and flake foods. The idea is to remember that they require smaller, sinking meals. Coolies should always be fed at night.
When it comes to living meals, bloodworms, glass worms, tubifex, and daphnia are all welcome. The next best choice is to buy frozen versions of these meals. To supplement dry foods, feed live or frozen items a couple of times each week.
When coolie loaches are not reproducing, there are no obvious variations between them. Males have bigger pectoral fins, with the second ray thickening, according to some hobbyists. Females get considerably bigger while they are carrying eggs, sometimes to an extreme. It's even possible to see the green-colored eggs through the female's abdominal skin in some situations.
Breeding the Coolie Loach
Coolie loach breeding is difficult, however it has been done in captivity. The female will lay her eggs in the breeding tank, which should have low water levels, very dark illumination, and floating plants. The pH of the water should be about 6.5, and the hardness should be reduced. Spawning will be aided by dense vegetation. The more at ease the coolies get with their surroundings, the more likely they are to spawn.
Because coolies spawn in groups, keeping a bigger group will boost your chances of spawning. Fish do not achieve sexual maturity for two years, so if your fish are young when you get them, you may have to wait. To stimulate spawning, feed the fish plenty of live food.
Females will become exceedingly huge as they approach the time to deposit their eggs. When the female is ready to reproduce, she will lay bright green sticky eggs on the bottom of the floating plants. Once the eggs have been deposited, return the adult fish to their original tank to guarantee the most fry survive.
In around 24 hours, the eggs will hatch, and there might be hundreds of them. Infusoria, which is found in most adult living plants, is an excellent initial meal. Brine shrimp that have just hatched are also a fantastic first meal. Coolie loach fry can be fed commercially prepared or finely crushed flakes.
More Pet Fish Species and Further Research
If coolie loaches appeal to you, and you are interested in some compatible fish for your aquarium, check out:
Check out additional fish breed profiles for more information on other fish.