Family	Cobitidae
Origin	Southeast Asia
Social	Peaceful
Tank Level	Bottom
Minimum Tank Size	15 gallons
Diet	Omnivore, enjoys live foods
Breeding	Egglayer
Care	Intermediate
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

Originating from Southeast Asia, the coolie loach is indigenous to the streams of Borneo, Java, western Malaysia, Singapore, Sumatra, and Thailand. Originally named Cobitis kuhlii, and later changed to Acanthophthalmus kuhlii, the current scientific name of this fish is Pangio kuhlii. Many references still utilize former scientific names.

Pangio kuhlii is one of two dozen species of kuhlis, a number of which closely resemble each other. The subspecies Pangio kuhlii sumatranus and Pangio kuhlii myersi have been described based on differences in coloration and markings. P. sumatuanus (also known as the Sumatra Kuhli) has fewer and darker bands than Pangio kuhlii. Sporting even wider bands is the Pangio kuhlii myersi. Although Pangio kuhlii remains the most popular and readily available of the coolie loaches, it is not unusual to purchase an incorrectly named loach.

Colors and Markings

Coolie loaches have an eel-like body that is yellow to pink in color, with multiple dark brown bands or stripes that partially or fully encircle the body. The body and stripe color patterns vary based on subspecies. The coolie loach possesses no lateral line, the fins are small, and the dorsal fin is located on the lower third of the body, much closer to the tail than the head.

The eye of the coolie is covered by a thin layer of transparent skin and is hidden under one of the dark bands. Below the eyes are a pair of sharp spines that rise if the fish is threatened, making it difficult for a predator to swallow them or for an owner to net them; take special care when doing so. The mouth of the coolie loach points downward and is surrounded by four pairs of barbels.

Tankmates

Coolie loaches are happiest when kept in groups of a half-dozen or more other coolies, and they are easily kept with non-aggressive fish. When kept singly they are quite shy and will remain hidden most of the time. Avoid keeping coolies with large or territorial fish, such as cichlids; instead choose small fish such as danios, rasboras, and tetras.

Coolie Loach Habitat and Care

In nature, the coolie loach lives in locations where there is clear, slow-moving water running over sand. They will tolerate a range of water parameters but prefer water on the acidic side with slightly colder temperatures in the mid-70s Fahrenheit. The smooth substrate is a must as these obligate burrowers will be injured by substrates having rough edges. Sand is the preferred substrate for these fish.

Make sure the tank is tightly covered as coolie loaches will jump out of the tank, particularly when startled. The inlet tube on the filter needs to also be covered with mesh or a sponge, as there are many documented cases of loaches swimming up the inlet tube and getting trapped in the filter. Owners have reported cases in which coolie loaches have disappeared for months, only to be found under the UGF or inside a canister filter, still very much alive. Take a headcount on your coolies to ensure you haven’t lost one or the lost fish may suffer and starve.

Coolie tanks should have plenty of safe hiding places, preferably in low, live plants when possible. Rocks, driftwood, and caves are all the best decor for coolie loaches. Keep lighting subdued, however, a well-lit tank is suitable as long as it is heavily planted, thus offering shady places for the loaches to hide. Place a moonlight in the tank so you can observe their nocturnal activities.

Coolie Loach Diet and Feeding

Live foods are the preferred diet for coolie loaches. However, they will accept a variety of foods, including frozen, freeze-dried, tablets, wafers and flake foods. The key is to remember that they need smaller foods that will sink. Always feed coolies at night.

When it comes to live foods, bloodworms are readily accepted as well as glass worms, tubifex, and daphnia. Frozen versions of these foods are the next best option. Feed live or frozen foods a couple of times per week to augment dry foods.

Gender Differences

There are no readily discernible differences between coolie loaches when they are not breeding. Some hobbyists have observed that males have larger pectoral fins, with thickening of the second ray. Once females are carrying eggs they become noticeably larger, sometimes in the extreme. In some cases, it’s even possible to see the green-colored eggs through the skin of the female’s abdomen.

Breeding the Coolie Loach

Breeding of coolie loaches is challenging, but it has happened in captivity. The breeding tank should have low water levels, very dim lighting, and floating plants, which will be used by the female when laying her eggs. Water pH should be about 6.5, and the water hardness should be lowered. Dense vegetation will help promote spawning. The more comfortable the coolies become with their environment, the greater the chance of spawning.

Because coolies are communal spawners, keeping a larger group will increase the likelihood of spawning. Fish do not reach sexual maturity for two years, which means you may have to be patient if your fish are young when you purchase them. Condition the fish with plenty of live food to encourage spawning.

As females near the time to lay their eggs, they will grow very large. When ready to spawn, the female will release bright green adhesive eggs, usually on the underside of the floating plants. To ensure the greatest number of fry survive, remove the adult fish to their original tank once the eggs have been laid.

Eggs will hatch in approximately 24 hours, and they can number up to several hundred. Infusoria, generally present in mature live plants, is an ideal first food. Freshly hatched brine shrimp are also a good first food. Commercially prepared fry food or finely crushed flakes are suitable as food for coolie loach fry.

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 freshwater fish.

While investigating the mantis shrimp, we found mixed opinions about these marine animals. Some aquarists find them interesting and enjoyable pets, while others see them as a threat to any aquarium. Let’s explore their characteristics and nature so you can decide if you want to keep one.

What Are Mantis Shrimp?

Found in tropical waters worldwide, they belong to the phylum Crustacea, class Malacostraca, subclass Hoplocarida (meaning “armed shrimp”), and order Stomatopoda. Often referred to as stomatopods, they come in a wide variety of species. As carnivores, they will eat almost anything, making them expert hunters. They are solitary animals, and unless you have a large tank, they should be kept alone.

Mantis shrimp have two hunting styles: “spearers” and “smashers.” “Spearers” use a spear-like claw to silently stab soft-bodied prey, while “smashers” use a powerful, club-like claw to break or crush hard-bodied prey. “Smashers” have a strike force comparable to a .22-caliber bullet and are known as “thumb splitters.” It’s rumored that their strength is enough to crack aquarium glass!

Mantis shrimp are burrowers and create tubes or cavities in sand, rubble, or mud. They adapt to living in holes, cracks, or crevices in rocks, and can reside in snail or hermit crab shells. A mantis shrimp might unexpectedly appear in your tank by hiding on a live rock due to their excellent hiding skills!

Some mantis shrimp species can grow up to 12 inches long. A notable six- to eight-inch black and white striped species can be found on the mudflats in Hawaii, which should not be underestimated.

Common Sign of a Mantis Shrimp

When fish, crustaceans, and invertebrates start mysteriously disappearing from your aquarium, many aquarists suspect a mantis shrimp. While this is a key sign of their presence, other marine animals could also be the cause. Consider a mantis shrimp as a suspect, particularly if fish are disappearing, but thoroughly investigate other possibilities before jumping to conclusions.

Popping Noises: Mantis Shrimp vs. Pistol Shrimp

Some believe clicking, popping, or snapping sounds from your tank indicate a mantis shrimp. Others argue these noises suggest a pistol shrimp instead.

If you have a pistol shrimp, suspect it for the sounds. However, pistol shrimp are unlikely to attack or kill fish but may punch holes in hermit crab, snail, and other mollusk shells to feed.

As natural burrowers, mantis shrimp create tubes or cavities in sand, rubble, or mud. Look for holes or tunnels with mounds of sand or rubble outside them. Pistol shrimp also exhibit this behavior, so if you spot such a hole, dim the tank lights and observe what emerges.

Mantis Shrimp: Pest vs. Pet

In the aquarium hobby, mantis shrimp are often regarded as monstrous creatures. This reputation is understandable for aquarists who have lost valuable specimens to them.

However, if a mantis shrimp accidentally enters your tank with new live rock, it’s not surprising that it behaves as a carnivore. While mantis shrimp might seem monstrous, they are simply doing what they naturally do: hunt.

Some aquarists love mantis shrimp for their hardiness and ease of care. They aren’t picky about tank conditions, are easy to feed, and are affordable to maintain. However, this doesn’t mean their environment can be neglected. Proper care is essential, as with any marine animal.

Adding a mantis shrimp to a fish-only or reef tank is generally not advisable. Their aggressive and territorial nature means they are best kept alone, although several can coexist in a very large tank with ample space.

How to Remove Mantis Shrimp from an Aquarium

Removing a mantis shrimp is challenging and requires patience. If one method doesn’t succeed, try another.

• Force it out with a stream of water. If the shrimp resides in live rock, wait for it to enter its hole. Place the rock in a bucket with saltwater. Use a turkey baster or syringe to squirt fresh water into the hole. The shrimp should eventually emerge.
• Dunk the rock in fresh water. Dunk the rock in fresh water.** Submerge the rock in a bucket of fresh water, but use this method only if you’re not concerned about losing other marine life on the rock.
• Wait it out. Remove the live rock and place it in a dry container or sink. With patience, the mantis shrimp may emerge, but this method often requires persistence as the shrimp can be just as patient.
• Catch it at night with a net. Mantis shrimp are nocturnal, so they’re best caught at night in a dark tank. Wait patiently and quickly scoop them with a net when they’re away from their burrow.
• Use natural predators like triggerfishes to combat them.
• Buy or make a trap. Many commercial traps are available for mantis shrimp, or you can build one yourself.

What to Do With a Mantis Shrimp

Once you remove the mantis shrimp from your tank, you have several options.

• Keep it and provide it with a tank of its own to live in.
• Ask a friend if they want it. Some aquarists enjoy keeping mantis shrimp.
• See if a local fish store with take it. They might even pay you for it.
• Contact a public aquarium in your area.  They might be interested in having it.