AquaLibs presents AquaRank Discover the world’s leading aquascapers

Explore transparent rankings built from published results across the world’s leading aquascaping contests.

Crossocheilus siamensis (Siamese Algae Eater)

Overview

The Siamese Algae Eater, scientifically known as Crossocheilus siamensis, is widely considered one of the most effective algae-eating fish in the aquarium hobby. Unlike many other species, they are famous for their willingness to consume stubborn black beard algae (BBA) and hair algae. Their energetic swimming patterns and diligent cleaning habits make them an invaluable addition to larger planted aquariums.

Distribution and Habitat

This species is native to the river basins of Southeast Asia, primarily found in Thailand, Malaysia, and parts of Indonesia. They inhabit heavily oxygenated streams and rivers with dense vegetation, submerged tree roots, and rocky bottoms. During the rainy season, they are known to move into flooded forests. The water in their natural habitat is typically clear, fast-flowing, and rich in oxygen.

Description of Siamese Algae Eater

Image of proboscis barb crossocheilus siamensis

Body shape:

They possess a slender, elongated, and torpedo-like body that is perfectly adapted for navigating fast-moving water currents and darting among dense plant life.

Color:

The primary body color is a silvery-grey or light brown, featuring a stark, bold black horizontal stripe that runs continuously from the tip of their snout all the way to the end of their tail fin.

Barbels:

They have a single pair of thin rostral barbels on their snout, which helps distinguish them from similar-looking species like the Flying Fox (which has two pairs).

Snout:

Their snout is slightly pointed and features a specialized downward-facing mouth designed for effectively scraping and grazing algae off flat surfaces and plant leaves.

Eyes:

The eyes are relatively large, clear, and positioned laterally on the head to provide a wide field of vision for detecting both food and predators.

Fins:

All of their fins are completely transparent or clear, lacking the red, yellow, or black markings often found on the fins of the similar-looking Flying Fox or False Siamese Algae Eater.

The Tail:

The tail is deeply forked and transparent. Crucially, the black lateral body stripe extends straight through the center of the tail fin, tapering to a point.

Temper

They are generally peaceful fish, especially when young. As they mature into adulthood, they can occasionally become mildly territorial toward their own kind or other bottom-dwelling species with similar body shapes, but they rarely cause physical harm to tank mates.

Sociality

While they can be kept singly, they exhibit their most natural behaviors when kept in small shoals of 3 to 5 individuals. In a community setup, they ignore most mid-to-top dwelling fish and do well with tetras, rasboras, and peaceful cichlids.

Activity

Siamese Algae Eaters are exceptionally active. They spend the majority of their day constantly grazing on plant leaves, driftwood, and aquarium glass. When resting, they possess a unique habit of propping themselves up on their pectoral and pelvic fins on the substrate or broad plant leaves.

Keeping and Caring for Siamese Algae Eater

Providing an environment that mimics their natural riverine habitat is the key to keeping these fish healthy and active. They require clean, well-oxygenated water and plenty of space to swim.

Tank size:

Due to their adult size of up to 15 cm (6 inches) and their highly active swimming nature, a minimum tank size of 100 liters (about 30 gallons) is recommended. Larger tanks are required if keeping a group.

Water Parameters:

Temperature

They thrive in tropical temperatures ranging between 24-26°C (75-79°F).

pH

The ideal pH level should be slightly acidic to neutral, ideally between 6.5 and 7.5.

Hardness

They prefer soft to moderately hard water, generally between 5 and 15 dGH.

Ammonia, Nitrite, Nitrate

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

Lighting

Moderate to high lighting is recommended. Not only does this support the growth of live plants, but it also encourages the natural growth of algae for the fish to graze on.

Water flow

Moderate to strong water flow is highly beneficial. Using a powerhead or a strong canister filter will simulate the fast-flowing streams of their native habitat and keep oxygen levels high.

Decorations and Plants

A heavily planted aquarium is essential. Include plenty of broad-leafed plants, smooth river stones, and large pieces of driftwood. These decorations provide ample surface area for algae growth and offer resting spots.

Diet

While they are celebrated for eating algae, they are true omnivores. In the aquarium, their diet of natural algae should be supplemented with high-quality sinking algae wafers, spirulina pellets, blanched vegetables (like zucchini or spinach), and occasional protein treats such as frozen bloodworms or brine shrimp.

Some Feeding Tips

Be careful not to overfeed them with commercial foods. If they realize that rich, easy-to-eat pellets are readily available, they may become lazy and completely stop eating the nuisance algae in your tank.

Breeding

Breeding the Siamese Algae Eater in a home aquarium is considered extremely difficult to impossible. In the commercial aquarium trade, breeding is almost exclusively achieved on large fish farms using hormone injections to induce spawning.

Conclusion

The Siamese Algae Eater is a fantastic, hard-working addition to medium and large freshwater aquariums. Their unrivaled ability to control difficult algae types, combined with their energetic and entertaining personalities, makes them a highly rewarding species for any dedicated aquarist.

Fish info

  • Care level: Easy - Moderate
  • Temperament: Peaceful
  • Adult size: 15 cm
  • Life expectancy: 10 years
  • Fish type: Cyprinid
  • Temperature : 24-26°C
  • pH: 6.5-7.5
  • Color Form: Black, Brown, Grey, Silver
Leave your comments
Latest on Fishs
  • Keyhole Cichlid (Aequidens maronii)

    Keyhole Cichlid (Aequidens maronii)

    Moderate
    South American freshwater cichlid
    The fish supplied is consistent with the keyhole cichlid, commonly listed as Aequidens maronii and currently placed by many authorities in the genus Cleithracara. It is a relatively peaceful South American cichlid recognized by its dark keyhole-shaped marking, subdued body coloration and interesting parental care. A pair needs a mature, well-filtered aquarium with soft surroundings, hiding places and stable water quality. Although generally manageable, it becomes territorial while spawning and should not be kept with boisterous or fin-nipping tank mates.
  • Marble Gourami (Cosby Gourami), Trichopodus trichopterus

    Marble Gourami (Cosby Gourami), Trichopodus trichopterus

    Easy - Moderate
    Freshwater labyrinth fish
    The marble gourami, commonly sold as the Cosby gourami, is a selectively bred color form of the three-spot gourami, Trichopodus trichopterus. It is a labyrinth fish that can breathe atmospheric air and generally occupies the upper and middle levels of a planted aquarium. This species is usually hardy, but adult males may become territorial, particularly when spawning. The supplied images show several color forms, so exact strain identification is not certain; the fish are best treated as marble or related cultivated forms of T. trichopterus.
  • Marble Gourami, Gold-Orange Form (Trichogaster trichopterus)

    Marble Gourami, Gold-Orange Form (Trichogaster trichopterus)

    Easy - Moderate
    Freshwater labyrinth fish
    The marble gourami is a selectively bred color form of the three-spot gourami, a labyrinth fish from mainland and island Southeast Asia. The supplied trade label identifies these fish as a gold-orange pair, although commercial names and appearance can vary, so the exact cultivated form is not fully certain. They are generally hardy community fish, but males may become territorial, especially when spawning. Provide warm, stable water, surface access, dense planting, and gentle filtration.
  • Honey Gourami Gold (Trichogaster chuna)

    Honey Gourami Gold (Trichogaster chuna)

    Easy - Moderate
    Small freshwater labyrinth fish
    The honey gourami is a small, peaceful labyrinth fish suited to planted freshwater aquariums. The supplied source identifies a gold pair as Colisa chuna, an older name now generally treated as Trichogaster chuna. The photographs show orange-gold individuals, but sex and exact variety cannot be confirmed from the images alone. Provide gentle flow, surface access, dense cover and calm tank mates for best results.
  • Honey Gourami (Colisa chuna) Care Guide

    Honey Gourami (Colisa chuna) Care Guide

    Easy - Moderate
    Small freshwater labyrinth fish
    The honey gourami is a small, peaceful labyrinth fish from the slow-moving waters of South Asia. Aquarium specimens may be natural honey-colored fish or selectively bred red and orange forms, like those shown here. The supplied images appear consistent with honey gourami, although sex cannot be confirmed reliably from the photographs. A planted aquarium with gentle flow, surface cover, stable warm water and calm tank mates suits this species well.
  • Blue Gourami (Trichogaster trichopterus) Care Guide

    Blue Gourami (Trichogaster trichopterus) Care Guide

    Easy - Moderate
    Labyrinth fish; freshwater anabantoid
    The blue gourami is a hardy labyrinth fish suited to a spacious, planted community aquarium. It is the blue color form of the three-spot gourami, a species that can become territorial, particularly when males mature or spawn. Provide gentle filtration, access to warm humid air above the water, hiding places, and a varied diet. The supplied images clearly show blue gouramis, although photographs alone cannot confirm sex or verify that every pictured fish belongs to the same color form.
  • Giraffe Perch (Nimbochromis venustus) Care Guide

    Giraffe Perch (Nimbochromis venustus) Care Guide

    Difficult
    Lake Malawi predatory haplochromine cichlid
    Nimbochromis venustus is a large predatory haplochromine cichlid from Lake Malawi, known in aquariums as the giraffe perch or giraffe cichlid. Juveniles are comparatively subdued, while adults develop blue facial tones and yellow, olive or gold body coloration with darker markings. The supplied listing describes two 4 cm fish as a pair, but sex cannot be confirmed reliably at that size. This species requires a spacious, rocky aquarium and carefully selected tank mates.
  • Dwarf Gourami (Trichogaster lalius)

    Dwarf Gourami (Trichogaster lalius)

    Moderate
    Small freshwater labyrinth fish
    The dwarf gourami is a small labyrinth fish from vegetated, slow-moving waters of South Asia. Trichogaster lalius is generally peaceful, colorful and suitable for a planted community aquarium, although males can become territorial, especially around a bubble nest. A pair needs warm, stable water, gentle circulation, surface access and plenty of cover. The supplied identification is consistent with dwarf gourami, though color varieties and sex should be confirmed by physical examination.
  • Five-Bar Cichlid (Neolamprologus tretocephalus)

    Five-Bar Cichlid (Neolamprologus tretocephalus)

    Difficult
    Lake Tanganyika rock-dwelling cichlid
    The five-bar cichlid, also called the five-striped cichlid, is a robust Lake Tanganyika predator with a dark blue-gray body marked by five broad black bars. Neolamprologus tretocephalus is territorial and can become highly aggressive, particularly when spawning. It suits experienced aquarists who can provide a spacious, rock-structured aquarium, alkaline hard water, and carefully selected tank mates. The supplied label identifies this fish as a pair, but sex and exact locality cannot be confirmed from the available information.
  • Gardner’s Splendid Carp (Fundulopanchax gardneri)

    Gardner’s Splendid Carp (Fundulopanchax gardneri)

    Moderate
    West African killifish
    Gardner’s splendid carp is a small West African killifish valued for its iridescent body, red markings and patterned fins. The supplied image appears to show a brightly colored male, while the source identifies a pair; exact locality form and sex of every fish cannot be confirmed from the available evidence. It is generally peaceful, though males may spar, and it is best kept in a covered, mature aquarium with gentle flow, subdued lighting and abundant plant cover.
  • Pelvicachromis taeniatus Nigeria Red

    Pelvicachromis taeniatus Nigeria Red

    Moderate
    West African dwarf cichlid
    Pelvicachromis taeniatus, commonly known as the striped krib or taeniatus cichlid, is a small West African riverine cichlid valued for its parental behavior and locality-based color variation. “Nigeria Red” identifies a trade form or collection locality rather than a separate species. The supplied source label also calls these fish emerald perch, but that common name is not a standard scientific name. This species is generally manageable for experienced beginners when provided with stable, clean water, hiding places and a carefully planned community aquarium.
  • Apistogramma agassizii ‘Fire Red’

    Apistogramma agassizii ‘Fire Red’

    Moderate
    South American dwarf cichlid
    Apistogramma agassizii is a small South American cichlid valued for its intricate markings, elongated fins and interesting parental behavior. “Fire Red” is a selectively bred aquarium color form rather than a separate species. The supplied listing describes a pair, although sex, locality and breeding-line identity cannot be confirmed from the available material. This species suits a mature, planted aquarium with soft, clean water, subdued lighting, cover and a fine substrate.
  • Cockatoo Cichlid Orange (Apistogramma cacatuoides)

    Cockatoo Cichlid Orange (Apistogramma cacatuoides)

    Easy - Moderate
    South American dwarf cichlid
    The Cockatoo Cichlid is a small South American dwarf cichlid known for its elongated dorsal fin, bold facial markings and colorful orange fin forms. Apistogramma cacatuoides comes from slow-moving waters and tributaries of the upper Amazon basin, where it shelters among leaf litter, roots and submerged vegetation. It is generally manageable for an aquarist who provides soft, clean water, caves and visual barriers. The supplied listing describes an orange pair, but sex and exact form should be confirmed by the seller because photographs alone are not definitive.
  • Dwarf Gourami Red (Trichogaster lalius)

    Dwarf Gourami Red (Trichogaster lalius)

    Easy - Moderate
    Asian labyrinth fish
    The red dwarf gourami is a selectively bred color form of the dwarf gourami, a small labyrinth fish formerly widely known as Colisa lalia. It is suited to mature, planted community aquariums with gentle water movement and calm tank mates. Males can be territorial, especially when kept with females in confined conditions, so cover, visual barriers, and careful observation are important for a pair.
  • Cockatoo Cichlid Red (Apistogramma cacatuoides)

    Cockatoo Cichlid Red (Apistogramma cacatuoides)

    Moderate
    South American dwarf cichlid
    The Cockatoo Cichlid is a small South American dwarf cichlid valued for its personality, breeding behavior and colorful finnage. Apistogramma cacatuoides is generally adaptable when provided with clean, stable water, cover and a soft substrate. Males are larger and more vividly marked than females, while pairs become territorial around spawning sites. The supplied “red” designation most likely refers to a selectively bred color form; exact strain and sex confirmation cannot be established from the listing alone.
  • Discus (Symphysodon aequifasciatus) Care Guide

    Discus (Symphysodon aequifasciatus) Care Guide

    Difficult
    South American freshwater cichlid
    Symphysodon aequifasciatus is a large, laterally compressed cichlid from the Amazon Basin, valued for its calm behavior and striking disc-shaped body. It requires warm, clean, stable water and careful feeding, making it better suited to experienced aquarists. The supplied images show yellow, orange, red, white and dark color forms; cultivated strains can vary considerably, so exact variety identification from images alone is uncertain. Discus are social fish and generally thrive in groups rather than as isolated specimens.