Glowlight Rasbora

Geographic Origin and Biotope: Endemic to Sumatra and Borneo (Jambi and Kapuas river basins). It is strictly a 'Blackwater' species: inhabiting ancient, dark Asian lowland peat swamps jammed with rotting detritus and branches, where sunlight struggles to pierce the jungle canopy.

Taxonomy and Morphology: Cyprinidae. The smallest and most fragile of the trio (heteromorpha-espei-hengeli), barely reaching 3 cm (1.2 inches). Extremely petite build and fine skeletal structure, with a partially transparent body.

Social Behavior: Extremely gregarious. Hyper-peaceful by nature, they terrify easily. MUST live in large, tight schools (minimum 12-15). They are constantly mid-water scouting, moving with slight nervous darts. Males perform brief, harmless criss-crossing chases.

Coloration and Sexual Dimorphism: Unlike the Espei (which is entirely copper-colored), the Hengeli has a pale, silver-gray, diaphanous body. The black mark is very thin and slender. The hallmark that gives it the name 'Glowlight' is a thin, incandescent stroke of brilliant neon orange painted EXACTLY above and in front of the black spot. Females have very rounded bellies; males are transparent and slender.

Tank Setup: Demands respect for its sensitive eyes and delicate nature: a 60 cm (24 inch) tank densely shaded by driftwood (Manila) and dozens of rotting Indian Almond leaves (Catappa) on the bottom to tint the water brown. The substrate MUST be dark. Floating plants are mandatory, and filter currents must be very gentle (sponge filter or spray-bar).

Feeding and Diet: Insectivorous micro-predator. The mouth is minuscule, inept at eating large foods. Accepts powdered pellets, but the dietary base for health must consist of vinegar eels, live newly hatched baby brine shrimp, and tiny daphnia. Standard frozen foods (like regular bloodworms) are often too large for their mouths.

Water Quality: Requires very soft water to manifest the neon color: GH 1-10, pH between 5.0 and 7.0 (they suffer in alkaline pH). Ideal temperature is between 23 and 28°C (73-82°F). They tolerate sharp osmotic-thermal swings or high nitrates very poorly.

Compatibility and Cohabitation: Perfect biotope companions for Boraras (Dwarf Rasboras), Kuhli Loaches, and Licorice or Chocolate Gouramis (Parosphromenus/Sphaerichthys), all of which love the same acidic blackwaters. Totally unsuitable to be housed with chaotic fish (Barbs, Danios) or Cichlids that would chew them up like peanuts. Highly safe for almost all Dwarf Shrimp.

Aquarium Reproduction: Difficult, precisely due to the water chemistry required (pH < 6.0 and GH < 3 needed to trigger hatching and prevent fungi). They lay dozens of eggs under submerged broad leaves by flipping upside down, copying the system of all Trigonostigma.

Risks and Diseases: They will waste away from starvation in overcrowded tanks or with violent tankmates. Highly sensitive to cutaneous fungal infections if attempted to be kept in hard, calcareous tap water without dissolved tannins.