Siamese algae eater - Crossocheilus siamensis

Scientific name: Crossocheilus siamensis

Common name: Siamese algae eater

Family: Cyprinidae

Usual size in fish tanks: 13 - 16 cm (5.12 - 6.3 inch)

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Recommended pH range: 6.5 - 8

Recommended water hardness: 4 - 18°N (71.43 - 321.43ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 23 - 27 °C (73.4 - 80.6°F)

The way how these fish reproduce: Spawning

Where the species comes from: Southeast Asia

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Middle levels

Short description

The Siamese algae eater (Crossocheilus siamensis) is one of the most effective algae-eating freshwater fish. It is valued for its ability to graze on black beard algae (BBA) and other problem algae that few fish will touch. They are peaceful, active schooling cyprinids that should be kept in groups of 5 or more in a spacious, well-oxygenated aquarium.

Origin

Native to Southeast Asia (Thailand, Cambodia, Laos, Malaysia). Found in rivers and streams with moderate current, sandy or rocky bottoms, and abundant aquatic vegetation.

Food and feeding

In the aquarium, SAE will graze constantly on algae films and soft vegetation. Provide a varied diet to keep them healthy: sinking algae wafers, spirulina pellets, blanched vegetables (zucchini, spinach, cucumber), and occasional protein foods (bloodworms, small crustaceans). Do not rely solely on algae; supplement feeding is essential once natural algae growth is reduced.

Sexing

Sexing is difficult. Mature females are usually larger and fuller-bodied than males, but there are no clear external differences.

Breeding

Crossocheilus siamensis has not been successfully bred in home aquaria on a regular basis. Commercial breeding is believed to occur in large outdoor ponds with the use of hormones. In captivity, reports of spontaneous spawning are extremely rare.

Lifespan

With proper care, Siamese algae eaters typically live 8–10 years, significantly longer than the 4–5 years often quoted.

Behavior & compatibility

SAE are peaceful community fish but very active, constantly darting around the tank. They do best with similarly sized, non-aggressive fish such as tetras, rasboras, rainbowfish, and gouramis. Avoid combining with aggressive cichlids or slow, delicate species. Keep in groups to reduce stress and to see natural schooling behavior.

Tank requirements

Tank size: minimum 150 L (40 gal) for a small group.
Aquascape: sand or smooth gravel substrate, driftwood, and hardy plants; leave open swimming areas.
Flow & oxygen: prefer moderate current and high oxygen levels; use strong filtration and aeration.
Water: pH 6.5–8.0, soft to moderately hard water, stable temperatures 23–27 °C.

Identification tips

True Siamese algae eater can be recognized by the continuous black stripe that runs from the tip of the snout through the tail fin. Unlike similar species (Epalzeorhynchos kalopterus, Crossocheilus oblongus), the stripe does not end before the tail and there are no colored edges on the fins. Correct identification is important, as only the true SAE eats black beard algae reliably.