freshwater
Siamese Algae Eater
Crossocheilus oblongus
Elongated body shape with a distinctive horizontal black stripe running from the snout, through the eye, all the way to the tip of the caudal fin. The body above the stripe is brownish-grey, fading to a silvery-white belly. They possess two pairs of barbels near the mouth and clear fins.
- Habitat
- Native to freshwater streams, rivers, and flooded forest…
- Size & weight
- Typically grows to a length of about 15 centimeters (6 i…
- Diet
- Primarily herbivorous and omnivorous.…
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Physical characteristics
Elongated body shape with a distinctive horizontal black stripe running from the snout, through the eye, all the way to the tip of the caudal fin. The body above the stripe is brownish-grey, fading to a silvery-white belly. They possess two pairs of barbels near the mouth and clear fins.
Habitat & distribution
Native to freshwater streams, rivers, and flooded forests in Southeast Asia, particularly the Mekong and Chao Phraya river basins. Prefers flowing, oxygen-rich waters with rocky substrates or dense vegetation.
Behavior
Generally peaceful and active swimmers, though they can become slightly territorial with their own kind as they mature. They are diurnal and spend much of their time actively browsing for algae.
Diet
Primarily herbivorous and omnivorous. Feeds extensively on various types of algae, including thread algae and black beard algae, while also consuming small insects, detritus, and plant matter in the wild.
Reproduction
Little is known about their natural breeding behavior in the wild, as they are pelagic spawners that do not practice parental care. Commercial breeding is typically induced using hormone injections.
Ecological role
Acts as an important grazer in freshwater ecosystems, helping to control excessive algae growth on rocks and aquatic plants, which maintains light penetration and overall habitat health.
Similar species
Often confused with the Flying Fox (Epalzeorhynchos kalopterus) and False Siamese Algae Eater (Garra cambodgiensis). The true Siamese Algae Eater has a black stripe that extends cleanly to the end of the caudal fin and lacks bright yellow or orange highlights on the fins.
Identification tips
Look for the unbroken black stripe running from the tip of the nose through the tailfin, a lack of prominent colored bands on the fins, and the presence of small barbels around the mouth.
Interesting facts
Unlike many other algae-eating fish, the Siamese Algae Eater is one of the few species known to readily consume stubborn black beard algae, making it highly valued in the freshwater aquarium hobby.