The Zodiac Loach has a beautiful ‘batik’ design, and an inviting sense of the tropics and the exotic!

The Batik Loach Nemacheilus triangularis, previously Mesonoemacheilus triangularis, is also called the Zodiac Loach. It is truly a distinctive and beautiful Hillstream Loach.

The Batik Loachhas a gray to whitish background color. It is patterned with angled brown to reddish stripes interspersed with spots. The stripes tend to intermittently merge in the center making a horizontal line back to the tail. When they get stressed or nervous they can drastically change color from lighter browns to very dark, almost black.

Unlike many of the Hillstream Loaches, the Batik Loach prefers warmer water. It is also nocturnal and quite shy. Provide subdued lighting and be sure to provide plenty of hiding and resting places created with rocks and driftwood. If they do not have adequate hiding places, they can become inactive and remain reclusive. They like to burrow so a substrate of sand or fine gravel is best. Plants are not necessary but they are a nice addition.

Batik Loaches are hardy, personable, and generally peaceful. They are good for a community aquarium, but with reasonably robust tank mates. They can and will defend their territory nipping the fins of others, especially when feeding. They are best kept singly. Only keep them with others of their own species, or similar loaches, if the aquarium is very large with ample hiding places for all.

Zodiac Loaches Having Fun

Scientific Classification


Batik Loach – Quick Aquarium Care

Aquarist Experience Level:Intermediate
Aquarium Hardiness:Moderately hardy
Minimum Tank Size:30 gal (114 L)
Size of fish – inches4.7 inches (11.99 cm)
Temperature:77.0 to 86.0° F (25.0 to 30.0&deg C)

Habitat: Distribution / Background

The Batik Loach Nemacheilus triangularis (previously Mesonoemacheilus triangularis) was described by Day in 1865. They are also called the Zodiac Loach. They are found in Asia, specifically India. These fish can be found within the Western Ghat mountains and through South India in the Manimala River which range in states of Kerala and Tamil Nadu.

The Batik Loach is listed on the IUCN Red List as least concern (LC). Nemacheilus triangularis is a widely distributed species occurring in the Western Ghats of three states of southern India. Although the species is harvested for aquarium trade and there is no monitoring, the population trends in this commonly occurring and abundant species is stable, hence Least Concern.

It occurs in a natural habitat of clear, well oxygenated headwater streams and rivers. The waters are usually in the middle of forests, so they are fairly shaded. The substrate consists of coarse sand, gravel, rocks and boulders covered in algae. Because of the substrate and fast moving water there is very little aquatic plant life. During the months on June and September the water are extremely fast due to the monsoon season. In nature these fish will eat other fish, crustaceans, insects, and plant matter.

  • Scientific Name: Nemacheilus triangularis
  • Social Grouping: Solitary – Can be kept in groups if tank is large enough and areas to hide.
  • IUCN Red List: LC – Least Concern – This is a commonly occurring and abundant species, so is stable.


The Batik Loach will get to about 2.5 inches (6.5 cm) in the aquarium, though in the wild it can attain lengths of 3 1/2 to 5 inches (9 – 12 cm). It iseasy to distinguish by the series of pale saddle like markings edged in black, running down along the dorsal side. As they age the markings become much more diverse. These fish are scaleless and have barbels on the lower part of the mouth.

  • Size of fish – inches: 4.7 inches (11.99 cm) – This fish often barely reaches 2 1/2 inches (6.5 cm) in the aquarium, although almost 4 inches (10 cm) is perfectly possible.
  • Lifespan: 10 years

Fish Keeping Difficulty

The Batik Loach can be hardy under the right conditions. They are not recommended for beginners because of their need for pristine water and they do not have scales. Not having scales makes them more prone to disease and very sensitive to medications used to treat disease. Experience in treating scaleless fish is very important to be able to give your loach a healthy and long life.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate

Foods and Feeding

Since theyare omnivorous, the Batik Loach will generally eat all kinds of live foods, sinking pellets and tablet foods, flakes, and algae. They like frozen foods as well. To keep a good balance give them a high quality flake or tablet food everyday. Feed mosquito larvae, brine shrimp (either live or frozen), tubifex, daphnia, and some vegetable foods such as algae wafers.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Most of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Most of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

Because the Batik Loach naturally occurs in areas with fast moving waters they require pristine water and can not tolerate accumulations of organic pollutants. Frequent water changes of about 30% a week are necessary.

  • Water Changes: Weekly – Water changes of about 30% weekly.

Aquarium Setup

The Batik Loach will swim in the bottom of the aquarium. They do well in a larger aquarium, ideally 30 gallons or so, with good water movement, subdued lighting, and places for retreat such as rocks, caves, and roots. They do best in soft to medium, slightly acidic water.

The tank setup for the Batik Loach should resemble its natural habitat, a flowing river with variiably-sized stones, mixed with sand and larger rocks scattered around. The substrate can to be a fine or medium gravel that does not have sharp edges. Have some rocks and driftwood arranged to make a maze of caves and shaded areas. Java ferns and Bolbitis will make a great addition to this environment.

Using an external power filter will work best, with power heads making a good amount of water movement in the lower portion of the tank. That will help prevent anything uncleanfrom being left on the bottom. These fish also require a high proportion of dissolved oxygen which can also be accomplished by the filter and powerheads. Powerheads should be arranged to make a moderate to fast current in the tank. Large tanks should have a river tank manifold installed with unidirectional flow.

  • Minimum Tank Size: 30 gal (114 L)
  • Substrate Type: Sand/Gravel Mix – Should be a varied substrate of gravel, sand, rocks, and boulders.
  • Lighting Needs: Low – subdued lighting
  • Temperature: 77.0 to 86.0° F (25.0 to 30.0&deg C)
  • Breeding Temperature: 76.0° F
  • Range ph: 7.0-7.5
  • Hardness Range: 5 – 18 dGH
  • Brackish: No
  • Water Movement: Strong
  • Water Region: Bottom – These fish are mostly bottom dwellers.

Social Behaviors

They should be kept singly as they can get aggressive to members of their own species and other similar loaches. This species is territorial and should be keptas the only loachunless there is plenty of room, and there are plenty of territorial markers in the tank. They can be kept in groups if the tank is large enough and has adequate areas to hide.

They are peaceful in a community aquarium with mildly aggressive tank mates, but they will defend their territory especially when feeding. Though they hide during the day, they can be lively and active in the evening or when feeding. Robust tankmates will do fine in the aquarium with it.

  • Venomous: No
  • Temperament: Semi-aggressive
  • Compatible with:
    • Same species – conspecifics: Sometimes – More than one can be kept as long as the tank is large enough and provides ample hiding places.
    • Peaceful fish (): Monitor – Fish that stay in the top and middle regions of the tank are normally safe.
    • Semi-Aggressive (): Monitor
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Monitor
    • Large Aggressive, Predatory (): Threat
    • Monitor – Larger slow swimmers should be fine. As long as they are not in the bottom of the tank they will not normally be looked at as prey.
    • Shrimps, Crabs, Snails: Threat – is aggressive
    • Plants: Safe

Sexual differences

It’s not easy to tell the difference between males and female Batik Loaches. Normally adult females will tend to grow slightly larger and have a rounder belly then males when gravid. When sexually mature, males should have a small suborbital flap and may develop thick pectoral fin rays with rows of tubercules.

Breeding / Reproduction

Little is known about breeding Batik Loaches and they are not yet bred commercially. However in 2004 a pair were successfully breed in the United States. The breeder used spawning mops and the eggs hatched 24 hours after fertilazation. The eggs needed to be removed quickly as the male started to eat them. The reported water temperaturewas 76° F.

  • Ease of Breeding: Moderate – Spawning in the aquarium is a rare occurrence, although there have been reports of success with use of a spawning mop.

Fish Diseases

Batik Loaches are scaleless and prone to disease, so take caution when introducing these fish to an established tank. The Batik is also very sensitive to medication to treat many diseases; a separate hospital tank is needed. Cold water and changes in water conditions can also cause stress to this fish which makes them even more prone to disease.

An outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping these sensitive types of fish, it is common to catch deteriorating water conditions and disease before other fish are affected. The best way to proactively prevent disease is to give your Batik Loach the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fishis more likely to acquire disease.

Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Batik Loach is occasionally available.



Featured Image Credit: Pavaphon Supanantananont, Shutterstock