The Zodiac Loach – Our Guide to This Fascinating Fish!

Alison Page

Alison Page


Zodiac Loach

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Zodiac loaches or Nemacheilus triangularis are also known as Batik loaches.

These small, nocturnal loaches are hardy and generally peaceful, making a good choice for a community tank.

Read this guide to learn more about how to care for the fascinating Zodiac loach.

Zodiac Loach Overview

Zodiac Loach Info
Scientific name:Nemacheilus triangularis
Common names:Zodiac loach, Batik loach
Care level:Intermediate
Behavior:Semi-aggressive, territorial
Size:2.5 to 4.7 inches
Lifespan:10 years
Minimum tank size:30 gallons
Water temperature:77° F to 86° F
Water parameters:pH range 7.0 to 7.5 Water hardness between 5 and 18 dGH

Batik Loach Species Profile

The Batik loach or Zodiac loach was first described in 1865 by Day and was initially named Mesonoemacheilus triangularis.

These loaches come from India, where they are widely distributed throughout the south of the country in the Manimala river, Tamil Nadu, and Kerala, as well as within the Western Ghat mountains.

Some harvesting of the fish for the aquarium trade takes place; however, according to the IUCN Red List, Zodiac loaches are not endangered and are classified as being of least concern (LC).

In the wild, Zodiac loaches live in clear, well-oxygenated hill streams and rivers, where the water movement is relatively fast. The natural habitat here is shady by the forest canopy and is generally dimly lit. The substrate is made up of algae-covered boulders, rocks, gravel, and coarse sand.

Since the water is fast-moving, there is little aquatic planting. This is especially the case during the monsoon seasons of June and September.

The Zodiac loach’s wild diet consists of crustaceans, plant matter, insects, and other fish.


Zodiac loaches grow to around 2.5 inches long in the aquarium. However, wild fish can reach up to 5 inches.

The fish have pale markings like saddles ringed in black extending down the length of the dorsal side. As the fish mature, the markings become more diverse. These loaches are scaleless and have characteristic babels on the lower part of their mouth.

If kept in optimum conditions and fed a suitable diet, Zodiac loaches can live for roughly 10 years.

Zodiac Loach Care Guide

In this part of our guide, we discuss how to care for the Zodiac loach.

Are Zodiac Loaches Suitable For Beginners?

Nemacheilus triangularis can be a hardy fish when given the right conditions. However, we do not recommend these fish for beginners to the hobby. Zodiac loaches are highly sensitive to organic pollutants and need pristine, clean water to thrive.

These loaches do not have scales. Scaleless fish are much more susceptible to disease and parasite attacks than fish with scales. In addition, scaleless fish are highly sensitive to many fish medications that are used to treat common fish diseases.

So, ideally, you need experience in treating scaleless fish to ensure a healthy, long life for your Zodiac loaches.

What Do Zodiac Loaches Eat?

Batik loaches are omnivores and are relatively easy to cater to.

The fish will take any kind of live foods, tablet foods, fish flakes, and sinking pellets. You can also feed the Zodiac loach a selection of frozen foods, and they will happily graze on any algae that are growing in your tank.

A well-balanced diet for Batik loaches could include:

  • tropical fish flakes
  • tablet foods
  • frozen mosquito larvae, bloodworms, brine shrimp, and daphnia
  • algae wafers

Although Zodiac loaches love live foods, we don’t recommend that you use a live diet for your fish unless you can be confident that your supplier is reliable. Live foods can often come with a cargo of parasites and bacteria that could infect your entire aquarium. So, it’s better to offer your fish frozen meaty foods instead.

Feeding Frequency

Feed your Zodiac loaches two or three times per day, offering only what the fish will eat in a few minutes.

Since these are shy, nocturnal fish, it’s better to use an automatic fish feeder to deliver the food in the evenings.

Tank Size

These fish need a large tank of at least 30 gallons.

Zodiac loaches prefer to swim at the bottom of the aquarium, so a rectangular tank is the best choice.

Although these fish don’t jump, we recommend that you choose a tank with a lid. A cover keeps dust and dirt from getting into the water, helping to keep the habitat clean for the fish. In addition, a large surface area helps to facilitate efficient gaseous exchange, oxygenating the water for the fish.

Tank Setup

To provide the best setup for your fish, you should try to replicate the natural environment as closely as possible.

So, use a smooth substrate of sand mixed with gravel and dotted with variably-sized rocks. The lighting should be dim, and you should provide plenty of driftwood, rocky overhangs, stones, and twisted roots where the fish can hide.

Lush planting is a good addition, too, especially Java fern and floating plant species.


As previously mentioned, Zodiac loaches need pristine water conditions and fast-flowing water.

So, we recommend using an external power filter with powerheads to provide plenty of water movement throughout the lower part of the tank. That helps to remove any organic waste from the bottom of the water column. Powerheads can also assist in oxygenating the water.

We recommend fitting a river tank manifold with a unidirectional flow if you have a very large tank.

Water Parameters

Zodiac loaches are tropical fish that require a water temperature of 77° F to 86° F, a pH level of between 7.0 and 7.5, and water hardness in the range of 5 to 18.

These fish cannot tolerate brackish water conditions.

Aquarium Maintenance

Since Batik loaches live in fast-moving waters, they require pristine water and cannot survive in dirty conditions that are high in organic pollutants.

For that reason, you need to carry out frequent water changes of up to 30% per week.

Tank Mates

You can keep Batik loaches in a community environment with semi-aggressive, robust tank mates. However, these fish will defend their territory aggressively when feeding.

Ideally, you should choose fish that gravitate toward the middle to upper regions of the water column.

It’s not recommended that you keep more than one Zodiac loach unless you have a very large aquarium with plenty of territorial markers and hiding places.

Invertebrates, such as snails, shrimp, crabs, etc., should be avoided since the Zodiac loach will regard these creatures as a food source.

Breeding Zodiac Loaches

All Zodiac loaches that you see in the trade are wild-caught since these fish are not yet bred commercially.

Spawning in the captive fish tank environment is highly unusual. However, it’s reported that a US fish keeper successfully bred a pair of these fish way back in 2004. Spawning mops were used, and the reported water temperature in the breeding tank was 76° F.

The eggs hatched extremely quickly, only 24 hours following fertilization. The eggs were moved immediately as the male fish began eating them.

Sexual Differences

If you do decide to try breeding from your Batik loaches, your first challenge is differentiating between the sexes, which is no easy task!

However, adult female loaches are usually slightly larger than males and have a plumper appearance when gravid. Sexually mature male Zodiac loaches have a small suborbital flap, sometimes developing thick pectoral fin rays with lines of tubercules.

Health and Diseases

Although Zodiac loaches are pretty hardy creatures, they are scaleless fish and are, therefore, prone to diseases.

That can present a problem when adding these loaches to an existing setup, as the stress of that can allow parasites such as Ich to attack the fish.

Unfortunately, scaleless fish, in general, are highly sensitive to much of the medication that’s used to treat many common fish ailments. For that reason, we suggest that you always transfer your Zodiac loaches to a separate hospital tank for treatment.

The Batik loach is also adversely affected if the water in the tank is too cold or if the parameters change dramatically. That stresses the fish, leaving them even more vulnerable to disease.

If you notice any signs of disease in your loaches, you might find that the outbreak can be limited to an individual or a few fish if you deal with the problem early on.

Disease Prevention

When keeping Zodiac loaches, you must monitor the water conditions in your tank and take care to spot other signs of disease before your other fish are affected.

Provide the fish with the correct water conditions, a suitable environment and habitat, and a high-quality, well-balanced diet. That ensures lower stress levels for the fish, making them less vulnerable to disease.

Whatever you introduce to your aquarium can bring disease and bacteria with it. That includes new fish, plants, decorations, and live food. So, before adding anything new to your tank, take care to clean it properly, and quarantine new fish for at least two weeks.


The Batik Loach is occasionally available from specialty dealers, generally retailing for around $20.

Final Thoughts

Did you enjoy our guide to the unusual, fascinating Zodiac loach? If you did, please take a moment to share the article before you go.

Zodiac loaches are small, semi-aggressive bottom-dwellers that can live in a community tank with other similar-natured fish that tend to hang out in the upper areas of the water column. These scaleless fish are not suitable for beginners since they are highly sensitive to water conditions and common fish diseases.

However, the Zodiac loach makes an unusual addition to your tank if you have experience in keeping scaleless fish.

Do you have a Zodiac loach? Perhaps you successfully bred your fish? Tell us in the comments box below.

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