Fire Rasbora / Pearly Rasbora

Geographic Origin and Biotope: Endemic to the Kalu, Kelani, Gin, and Nilwala river basins in southwestern Sri Lanka. Inhabits small, pristine rainforest streams and pools shaded by dense canopies, loaded with decaying leaves and tangled branches.

Taxonomy and Morphology: Cyprinidae. Formerly known as Rasbora vaterifloris, moved to its own genus Rasboroides. Has a curious body shape for a rasbora: not torpedo-like, but short, very stocky, and diamond-shaped (deep-bodied), resembling a small tetra. Reaches barely 4 cm (1.5 inches).

Social Behavior: Extremely placid and reserved, if not nervous. If placed in tanks that are too bright or with dynamic fish, it will fade to a transparent gray and hide permanently. In a school of 10+ specimens, in a proper environment, males will display fascinating submission/dominance dances with fully extended fins.

Coloration and Sexual Dimorphism: Several natural color variants exist in Sri Lanka. The most famous is the 'Fire' variant, with a rust, bright orange, or matte red body, and fins of the same color. There is also a lemon/pear yellow variant ('Pearly'). Males have vastly more saturated colors and pointed fins; females are chubby and pale yellow.

Tank Setup: Demands a Blackwater aquarium of at least 60-80 cm (24-32 inches). The filter must be set to the absolute minimum: they loathe currents. The perfect layout consists of fine inert sand, knotty driftwood reaching the surface, an abundance of Ketapang leaves on the bottom, and Cryptocoryne wendtii. Light must be almost totally shielded by floaters.

Feeding and Diet: Finicky micro-predators/insectivores. Because of their tiny, upward-facing mouth, they struggle to feed on the bottom or with hard pellets. It is essential to provide tiny live food: drosophila (fruit flies), baby brine shrimp, and daphnia. They adapt slowly to crushed dry flakes.

Water Quality: Intolerant of hard, calcareous water. Categorically require GH between 1 and 5 and strongly acidic pH (5.5 - 6.5). A biologically mature and intact environment (with spontaneous microfauna) prevents immune crashes. Ideal temperature 23-28°C (73-82°F).

Compatibility and Cohabitation: MUST be housed EXCLUSIVELY in species-only tanks or with extremely slow and mild companions, like Sri Lankan micro-Puntius (Cherry Barbs), Kuhli Loaches, or Otocinclus. Never pair with Tiger Barbs, Zebra Danios, or Cichlids: the Fire Rasbora would literally die of fright.

Aquarium Reproduction: Egg-scatterer among fine plant filaments. Quite delicate. Eggs and fry are light-sensitive and easily succumb to fungus in waters lacking sufficient tannins.

Risks and Diseases: They quickly succumb to cutaneous bacterial infections and instantly lose their orange color if forced to live in clear, hard waters or with tankmates that are too aggressive at feeding time.