Eirmotus octozona (Eight-banded Barb)

02 July 2026

416

The Eight-banded Barb is a peaceful, shy, and captivating schooling fish native to the blackwater swamps of Southeast Asia. Known for its striking vertical black stripes over a semi-transparent body, it is a highly sought-after species for aquarists looking to build a serene, planted, or biotope aquarium.

Overview

Image of eight banded barb eirmotus octozona

The Eight-banded Barb (Eirmotus octozona) is a small, relatively rare cyprinid that brings a unique and delicate aesthetic to the freshwater aquarium. Because of their shy nature and specific water requirements, they are best suited for aquarists who can provide a dedicated, well-maintained environment. When kept properly in a group, their schooling behavior and distinct banding make them a fascinating centerpiece for smaller tanks.

Distribution and Habitat

This species is native to Southeast Asia, with populations primarily found in southern Thailand, Peninsular Malaysia, and parts of Indonesia (Borneo and Sumatra). They naturally inhabit slow-moving blackwater streams, peat swamps, and forest pools. These habitats are characterized by soft, highly acidic water stained brown by decaying organic matter, such as fallen leaves, submerged roots, and branches.

Description of Eight-banded Barb

Body shape:

They possess a small, somewhat laterally compressed, and deep-bodied torpedo shape typical of many small barbs, allowing them to navigate efficiently through dense vegetation.

Color:

The base body color is a pale, semi-transparent silver or light tan. Their most defining feature is the series of eight distinct, vertical black bands running from the snout to the caudal peduncle.

Barbels:

Like many members of the cyprinid family, they possess very small, barely noticeable sensory barbels near the mouth to help locate food.

Snout:

The snout is relatively short and slightly pointed, equipped with a small terminal mouth designed for picking micro-prey from the water column and surfaces.

Eyes:

They have proportionally large eyes, which are crossed by the very first vertical black band, helping to camouflage the eye from potential predators.

Fins:

The fins are mostly translucent. The dorsal fin is tall and sometimes exhibits faint dark markings or a slight reddish hue near the base, as seen in adult specimens.

The Tail:

The caudal fin (tail) is deeply forked and completely clear, aiding in quick, darting movements when the fish feels threatened.

Temper

The Eight-banded Barb is exceptionally peaceful but can be quite timid and easily outcompeted for food. They are easily stressed by aggressive or overly boisterous tank mates.

Sociality

They are a highly social, schooling species. To ensure they feel secure and display their best natural behaviors and colors, they must be kept in a group of at least 8 to 10 individuals.

Activity

They are generally active in the middle to lower levels of the aquarium. While they spend much of their time gently hovering or exploring the substrate and plant leaves, they will quickly dart into hiding if startled.

Keeping and Caring for Eight-banded Barb

Tank size:

A minimum tank size of 60 liters (15 gallons) is recommended for a proper school. A longer footprint is preferred to give them adequate horizontal swimming space.

Water Parameters:

Temperature

They thrive in warm tropical waters, with an ideal temperature range of 22-26°C (72-79°F).

pH

Being native to blackwater environments, they prefer acidic water. Maintain the pH between 5.0 and 7.0 for optimal health.

Hardness

Water should be very soft, ideally between 1 and 10 dGH.

Ammonia, Nitrite, Nitrate

Ammonia and Nitrite must always be at 0 ppm. Nitrates should be kept as low as possible, ideally below 20 ppm, through regular water changes.

Lighting

Lighting should be dim to moderate. Floating plants can be used to diffuse bright lights, which helps reduce stress and encourages the fish to venture out into the open.

Water flow

Water flow should be gentle and sluggish, mimicking their natural slow-moving swamp and forest pool habitats.

Decorations and Plants

A dark, sandy substrate mixed with dried leaf litter (such as Indian Almond leaves), driftwood branches, and dense plantings of shade-tolerant species (like Cryptocoryne, Java Fern, and Anubias) will create a perfect biotope. The tannins released by the wood and leaves will also condition the water to their liking.

Diet

In the wild, they are micropredators feeding on tiny insects, worms, and zooplankton. In the aquarium, they are unfussy and will accept high-quality crushed flakes or micro-pellets. This should be heavily supplemented with small live or frozen foods such as Daphnia, baby brine shrimp (Artemia), and bloodworms to maintain peak coloration and health.

Some Feeding Tips

Because they possess small mouths and can be timid, ensure that the food particles are small enough for them to consume and that faster tank mates do not steal all the food before it reaches them. Feed small amounts 1 to 2 times daily.

Breeding

Breeding the Eight-banded Barb can be somewhat challenging. They are egg-scatterers that provide no parental care. To breed them, set up a separate, dimly lit spawning tank with very soft, acidic water and cover the bottom with a spawning mop or fine-leaved plants like Java Moss. Condition the adults with high-quality live foods. Once eggs are scattered, the adult fish should be removed immediately to prevent them from eating the eggs. The fry are extremely tiny and will require infusoria or paramecium until they are large enough to accept newly hatched brine shrimp.

Conclusion

The Eight-banded Barb is a beautiful, understated gem of the aquarium hobby. While they require a bit more attention to water parameters and careful selection of tank mates, their peaceful schooling nature and striking barcode-like pattern make them a highly rewarding species for a dedicated blackwater or planted aquarium setup.

Fish info

Care level: Moderate
Temperament: Peaceful
Adult size: 3-4 cm
Life expectancy: 3-5 years
Fish type: Cyprinid
Temperature : 22-26°C
pH: 5.0-7.0
Color Form: Black, Clear, Silver, Tan

Related on Fishs

Leave your comments

Latest on Fishs

Julidochromis transcriptus: Black-and-White Slender Cichlid

Moderate

Lake Tanganyika rock-dwelling cichlid

Julidochromis transcriptus is a small rock-dwelling cichlid from Lake Tanganyika, recognized by its compact, elongated body and irregular black-and-white pattern. It is a territorial cave dweller that is best kept as an established pair in a carefully structured aquarium. The supplied fish are identified as a DNZ pair, although sex, collection locality, and precise geographic form cannot be verified from the supplied material alone.
Azur Cichlid (Sciaenochromis fryeri) Care Guide

Moderate

Lake Malawi haplochromine cichlid

The Azur cichlid is commonly sold as Sciaenochromis fryeri, a predatory haplochromine cichlid from Lake Malawi. Mature males develop vivid electric-blue coloration, while females and juveniles are generally less intensely colored. This fish is moderately aggressive and needs a spacious aquarium with rocky structure, alkaline, mineral-rich water, and carefully selected tank mates. The supplied source describes a DNZ pair, but sex and exact locality cannot be confirmed from the images alone. Identification confidence is therefore good but not absolute.
Marble Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The marble angelfish is a captive-bred color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular black patterning. It needs a mature, spacious aquarium with excellent water quality, warm water and suitable tank mates. Although generally manageable, adults establish territories and may become assertive when pairing or spawning. The supplied source identifies two marble angelfish; exact lineage and strain details cannot be confirmed from the available information.
Gold Angelfish, Pterophyllum scalare

Moderate

Freshwater South American cichlid

The Gold Angelfish is an ornamental colour form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its graceful movement and parental care. It needs a mature, spacious aquarium with substantial vertical clearance, stable warm water and carefully chosen tank mates. The supplied source identifies two fish as Gold Angelfish, although the accompanying images show several angelfish colour and fin forms, so the exact appearance of the supplied specimens cannot be confirmed from the images alone.
Zebra Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The Zebra Angelfish is a selectively bred form of Pterophyllum scalare, recognised by a silvery body with several dark vertical bars and the tall, laterally compressed shape typical of freshwater angelfish. The supplied images also show other angelfish colour forms, so the exact appearance of the listed pair cannot be confirmed from the image set alone. This South American cichlid is generally manageable for experienced community keepers, but its size, territorial breeding behaviour and need for a tall aquarium should be planned for carefully.
Black Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The supplied record identifies two black angelfish, most likely a domestic color form of Pterophyllum scalare. The photographs show several angelfish color patterns, so they should not be treated as proof that every pictured fish is black or that all belong to the same strain. Black angelfish retain the tall, laterally compressed body and extended fins typical of freshwater angelfish. They need a tall, mature aquarium, stable warm water, a varied diet, and carefully selected tank mates.
White Marble Angelfish (Pterophyllum scalare)

Moderate

Freshwater cichlid

The white marble angelfish is a selectively bred aquarium color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular dark marbling. It is generally peaceful when young but can become territorial, especially when paired for spawning. Successful care depends on a tall aquarium, excellent water quality, suitable tank mates, and a varied carnivorous-omnivorous diet. The exact genetic strain shown cannot be confirmed from photographs alone.
Freshwater Angelfish Mix (Pterophyllum scalare)

Moderate

Freshwater cichlid

Freshwater angelfish are tall-bodied South American cichlids valued for their graceful movement and wide range of captive color forms. The supplied source identifies a mixed group as Pterophyllum scalare; the photographs show several forms, including striped, black, orange, white, silver and blue-toned fish. They are manageable for experienced beginners, but their adult height, territorial breeding behavior and tendency to eat small tank mates require thoughtful aquarium planning.
Leopard Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The leopard angelfish is a domestic color form of Pterophyllum scalare, a tall-bodied freshwater cichlid from tropical South America. Its silver to yellowish body is marked with irregular dark spots or broken vertical bars, although pattern intensity varies with age, mood and breeding line. It is generally peaceful in a suitably spacious community aquarium, but pairs become territorial when spawning. This fish needs warm, clean water, generous vertical swimming space and tank mates too large to swallow.
Yellow Labidochromis (Labidochromis caeruleus)

Easy - Moderate

Lake Malawi mbuna cichlid

The Yellow Labidochromis is a bright yellow mbuna cichlid from Lake Malawi. Labidochromis caeruleus is generally manageable for an African cichlid, but it remains territorial and needs hard, alkaline water, rockwork, and carefully chosen companions. The supplied source identifies two fish as a pair; sex and pair bonding cannot be confirmed from the available images. This species is an adaptable algae grazer, a maternal mouthbrooder, and a rewarding choice for an appropriately planned Malawi cichlid aquarium.
Blue Pearl Angelfish (Pterophyllum scalare)

Moderate

Freshwater cichlid

The Blue Pearl Angelfish is a selectively bred colour form of Pterophyllum scalare, the freshwater angelfish. Its laterally compressed body, extended fins and tall profile make it a striking inhabitant of a planted community aquarium. The supplied trade label supports identification as this species and colour form, although individual colour intensity can vary. It requires warm, stable, clean water, generous vertical swimming space and thoughtful tank-mate selection, especially as adults become territorial when pairing or spawning.
Villavicencio Dwarf Cichlid Apistogramma macmasteri

Moderate

South American dwarf cichlid

Apistogramma macmasteri, commonly called the Villavicencio dwarf cichlid, is a small South American cichlid associated with the Río Orinoco drainage of Colombia. It is valued for its compact size, elaborate finnage and interesting courtship behavior. A bonded pair can be kept in a carefully structured aquarium with soft, clean water, sand, cover and several potential spawning sites. Although manageable for an experienced community aquarist, territorial behavior increases during breeding, so tank layout and tankmate selection are important.
Neolamprologus leleupi (Tanganyika Golden Cichlid)

Moderate

Lake Tanganyika rock-dwelling cichlid

Neolamprologus leleupi is a small, brightly coloured cichlid endemic to Lake Tanganyika in East Africa. It inhabits rocky coastal areas and uses crevices for shelter, feeding and spawning. Despite its modest size, it can be strongly territorial, particularly when paired or breeding. The supplied source identifies these fish as a golden colour form and a pair, although sex cannot be confirmed reliably from the image alone. Successful care depends on alkaline, mineral-rich water, abundant rockwork and carefully chosen tank mates.
Maingano Cichlid (Melanochromis cyaneorhabdos)

Moderate - Difficult

Lake Malawi mbuna cichlid

The Maingano, or Johanni Maingano, is a Lake Malawi mbuna recognized for its intense steel-blue body and dark horizontal markings. The supplied label combines “Johanni” with the scientific name Melanochromis cyaneorhabdos; these are distinct species, so identification should be confirmed from the seller or locality. This territorial mouthbrooding cichlid needs hard, alkaline water, abundant rockwork, a predominantly algae-based diet, and careful stocking to limit aggression.
Red Chocolate Gourami (Sphaerichthys vaillanti)

Difficult

Blackwater labyrinth fish

The red chocolate gourami, Sphaerichthys vaillanti, is a specialized Southeast Asian labyrinth fish suited to mature, soft, acidic blackwater aquariums. It is peaceful but easily stressed by bright lighting, strong currents and boisterous tank mates. The supplied source identifies these fish as a pair; sex and exact identity cannot be confirmed from the image alone, so identification should be checked against a reliable specimen reference. Stable water quality, cover and a varied small-food diet are central to long-term success.
Pelvicachromis pulcher Purple Tilapia Pair Care Guide

Easy - Moderate

Small West African freshwater cichlid

Pelvicachromis pulcher, commonly called the kribensis or purple cichlid, is a small West African cave-spawning cichlid valued for its manageable size, attractive breeding colors and attentive parental behavior. A bonded pair can live in a community aquarium when provided with suitable cover and carefully chosen tank mates. The supplied listing identifies the fish as Pelvicachromis pulcher, although photographs alone cannot confirm the exact locality or color form.