Red Rainbowfish

Taxonomy

Kingdom: Animalia 

Phylum: Chordata 

Class: Actinopterygii

Order: Atheriniformes

Family: Melanotaeniidae

Genus: Glossolepis

Glossolepis incisus

Habitat & Distribution : Endemic to Lake Sentani, Papua, Indonesia

Diet : Algae, plankton, and detritus

Size: Up to 10-15 cm

Lifespan: Mencapai 8 tahun

Description

As the Red Rainbowfish matures, its body develops a deep, high-backed profile resembling a diamond shape, contrasting with its small head, pointed snout, and large eyes. Visible color differences between males and females emerge as the fish approach adulthood; females display more subdued coloration and possess elongated, transparent fins with olive-yellow hues, whereas males turn bright red once they reach a size of 5 cm.

Behavior

The red rainbowfish lives in large schools in the shallow areas of Lake Sentani, which are rich in aquatic vegetation and submerged wood. Dominant males perform rapid dancing movements while erecting their fins and intensifying their red coloration (flashing) to intimidate other males and attract females.

Reproduction

The mating process is triggered by the arrival of dawn, marked by a ritual in which the male illuminates a golden neon stripe on his forehead while performing an aggressive dance. During spawning, the fish act as egg scatterers, herding their partners into dense vegetation to deposit their eggs. This species is a partial spawner; the female does not release all her eggs at once but instead deposits 20 to 50 adhesive eggs daily, a process that continues over several weeks during the breeding season.

 Communication & Perception

The red rainbowfish relies heavily on a keen visual system and the mechanosensory sensitivity of its lateral line to adapt to the bright surface waters of Lake Sentani. Their large eyes are highly accurate at accounting for light distortion at the water's surface, while light reflecting off the scales of conspecifics facilitates the recognition of fellow school members. In addition to vision, they utilize a lateral line system—sensitive to changes in water pressure—to synchronize their swimming movements.

Predator

Snakehead fish, flowerhorn fish, and waterbirds