Crossocheilus oblongus

Crossocheilus oblongus is one of several related algae-eating cyprinids from mainland Southeast Asia that are closely allied to the true Siamese Algae Eater (C. siamensis/langei). It is a slender, elongated fish with a continuous dark mid-lateral stripe running from the snout to the tail, and like its relatives it is a diligent grazer of soft algae, diatoms, and organic detritus from surfaces.

In the aquarium it is generally more peaceful than the Flying Fox and less prone to the territorial behaviour occasionally exhibited by the SAE in smaller setups. It adapts well to standard community conditions and can serve as an effective algae management fish in planted tanks.

Crossocheilus oblongus is occasionally misidentified in the trade as the true SAE, highlighting the difficulty of distinguishing between species in this genus. Hobbyists should examine stripe characteristics carefully when purchasing to ensure they obtain the desired species.

Water: Temperature 24–28°C, pH 6.0–7.5, GH 5–15; good filtration and regular water changes maintain health; appreciates moderate current. Tank: Minimum 120 L; substrate foraging areas with smooth rocks and driftwood; some algae growth welcomed. Feeding: Algae wafers, blanched vegetables, pellets, and incidental live foods; a varied diet prevents nutritional deficiencies. Breeding: Not yet reliably bred in captivity; hormonally induced breeding occurs in commercial fish farms. Compatibility: Peaceful community fish; gets along with most medium to large fish; keep only one per tank in smaller aquariums to prevent minor territorial behaviour.