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Zig-Zag Eel: Characteristics, Diet, Facts & More [Fact Sheet]

The Zig-Zag Eel, scientifically known as Mastacembelus armatus, is a captivating species of freshwater fish, renowned for its unique appearance and behavior. Native to the rivers and wetlands of South and Southeast Asia, this eel-like fish is a subject of interest among aquarists and ecologists.

In this article, we delve into the world of the Zig-Zag Eel, exploring its classification, physical traits, natural behavior, and ecological significance, offering a thorough understanding of this intriguing freshwater species.

The Zig-Zag Eel at a Glance


Superclass:Osteichthyes (Bony fish)
Species:M. armatus

Essential Information

Average Size:Typically 35 to 40 cm (14 to 16 inches), can grow up to 90 cm (35 inches)
Average Weight:800-1000 grams
Average Lifespan:Up to 8-10 years in captivity
Geographical Range:South and Southeast Asia, including India, Sri Lanka, Bangladesh, Myanmar, Thailand, and Malaysia
Conservation Status:Least Concern (IUCN Red List)

Species and Subspecies

Mastacembelus armatus, commonly known as the Zig-Zag Eel, is a distinct species within the Mastacembelidae family. Mastacembelus armatus is a singular species with no recognized subspecies.

While this species is unique in its own right, the Mastacembelidae family comprises various species of spiny eels, each varying in size, color, and habitat preferences. The Zig-Zag Eel is particularly known for its elongated body with zig-zag patterns, setting it apart from its relatives who may have different body patterns and colorations.

Zigzag eelSource: Wikimedia Commons


The Zig-Zag Eel is distinguished by its distinctive physical characteristics. This species typically measures between 35 and 40 cm, with some individuals reaching up to 90 cm.

Its body is elongated and eel-like, with a series of dark zig-zag patterns along its length, which give it its common name. The body is generally brownish or grayish, with a lighter underside.

The Zig-Zag Eel is characterized by a long, slender body, a pointed snout, and a dorsal fin that runs almost the entire length of its body. It has small eyes and a mouth adapted for bottom feeding.

There is limited information on sexual dimorphism in this species. However, like many fish, males and females may differ slightly in size or coloration during the breeding season.

Habitat and Distribution

The Zig-Zag Eel is native to a broad region in South and Southeast Asia. Its range includes India, Sri Lanka, Bangladesh, Myanmar, Thailand, and Malaysia, among other countries in the region.

This species thrives in various freshwater habitats, including rivers, streams, ponds, and swamps. It prefers slow-moving or still waters with plenty of hiding places like rocks, vegetation, or debris.


The Zig-Zag Eel exhibits several interesting behaviors typical of bottom-dwelling freshwater fish. It is primarily nocturnal, becoming more active at night to hunt for food. During the day, it tends to hide in the substrate or among aquatic plants.

Zig-Zag Eels are generally solitary, especially when mature. They can be territorial and may show aggression towards others of their species in confined spaces, like aquariums.

There is little information available on their communication methods. Like many fish, they likely use body language and chemical signals to interact with one another.

These eels are skilled burrowers, often digging into soft substrates in their natural habitat. This behavior provides a protection from predators and creates an ideal environment for ambushing prey.

Diet and Feeding Behavior

The Zig-Zag Eel’s diet is indicative of its role as a carnivorous bottom-dweller. They primarily feed on small aquatic animals. This includes worms, crustaceans, insects, and occasionally small fish.

As nocturnal predators, Zig-Zag Eels actively forage at night. They use their elongated body and quick movements to ambush prey, relying on their keen sense of smell to locate food. Their burrowing behavior also aids in surprising prey from beneath the substrate.


In their natural habitat, Zig-Zag Eels face predation from larger aquatic species. Potential predators include larger fish and aquatic birds that prey on small fish and eels. Their nocturnal habits and burrowing behavior provide some defense against these threats.

Juvenile eels are more susceptible to predation due to their smaller size. As they grow larger, their risk of predation decreases, but they remain vigilant, especially when out of their burrows.

Reproduction and Life Cycle

The reproductive behavior of Zig-Zag Eels is not well-documented but follows general fish reproductive patterns. Details about their mating rituals in the wild are limited. In captivity, breeding is rare and challenging due to the specific environmental conditions required.

As with other fish, Zig-Zag Eels lay eggs. The development time of these eggs before hatching can vary but is generally in line with typical freshwater fish.

The number of eggs and the care of the young are not well-known. In many fish species, the young are independent from birth and receive little to no parental care.

The life cycle of the Zig-Zag Eel, from egg to adult, involves changes in habitat preference and behavior as they grow. Their adaptability to various freshwater environments plays a key role in their survival and development.

Conservation and Threats

The conservation status of the Zig-Zag Eel reflects the current understanding of its population and environmental impact. The Zig-Zag Eel (Mastacembelus armatus) has not been evaluated by the International Union for Conservation of Nature (IUCN), which means its global population trends and potential threats are not fully understood.

Potential threats to this species include habitat degradation, pollution, and overfishing, particularly in regions where environmental regulations may be less stringent.

Specific conservation efforts for the Zig-Zag Eel are not well-documented. However, general efforts to preserve freshwater ecosystems and maintain water quality indirectly benefit their populations.

Fun Facts

  1. Unique Burrowing Behavior: Zig-Zag Eels are known for their ability to burrow into soft substrates, creating hiding spots and ambush points for catching prey.
  2. Aquarium Popularity: They are a popular choice among freshwater aquarium enthusiasts due to their distinctive appearance and interesting behavior.
  3. Distinct Classification: Despite its eel-like appearance, the Zig-Zag Eel is distinctively classified in the Mastacembelidae family, separate from true eels found in the Anguilliformes order. This highlights the diverse range of body shapes and adaptations found within the fish category.
  4. Nocturnal Hunters: These eels are more active at night, using the cover of darkness to forage and explore their habitat.
  5. Elongated Anatomy: Their slender, elongated body allows them to navigate through tight spaces and crevices in their aquatic environment.

Frequently Asked Questions

What do Zig-Zag Eels eat?

Zig-Zag Eels primarily feed on small aquatic animals such as worms, crustaceans, insects, and sometimes small fish.

Where can Zig-Zag Eels be found?

They are native to South and Southeast Asia, inhabiting various freshwater habitats like rivers, streams, ponds, and swamps.

How long do Zig-Zag Eels live?

In captivity, they can live up to 8-10 years, but their lifespan in the wild may vary.

Are Zig-Zag Eels aggressive?

They can be territorial and may show aggression towards other eels, especially in confined spaces like aquariums.

Do Zig-Zag Eels require special care in aquariums?

Yes, they require specific water conditions, including temperature and pH levels, and a tank setup that mimics their natural habitat with hiding places.

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