Red-tailed Rasbora

The Red-tailed Rasbora (Rasbora borapetensis) is a lively and attractive schooling fish native to slow-moving streams, canals, and flooded rice paddies in Thailand and Myanmar. Growing to approximately 5 cm, it has a streamlined silver body adorned with a prominent black lateral stripe running from the snout to the base of the tail, and a distinctive bright red caudal fin that becomes more vivid in healthy, well-conditioned fish. The contrast between the dark stripe and the red tail makes this species particularly eye-catching when kept in groups. In the wild, Red-tailed Rasboras inhabit relatively calm, vegetated waters with neutral to mildly acidic pH and moderate hardness. In the aquarium, they are quite adaptable and can tolerate a range of water conditions within sensible limits, making them a good choice for intermediate to beginner hobbyists. A planted aquarium with open swimming areas is ideal. They are active mid-water swimmers and tend to shoal tightly when slightly startled, creating a beautiful synchronized display. They are peaceful toward all tankmates and mix well with other community fish of similar size, including tetras, other rasboras, small catfish, and livebearers. Red-tailed Rasboras are omnivores that accept a wide variety of foods including flake, micro-pellets, daphnia, and frozen or live bloodworms and brine shrimp.

Tank Setup: A minimum tank of 60 liters is recommended for a school of six or more. Provide open mid-water swimming space flanked by planting along the sides and back. Use fine-grained substrate, driftwood, and a mix of broad-leaved and fine-leaved plants to create cover and interest. Subdued lighting suits this species but standard planted tank lighting is also acceptable.

Water Parameters: Red-tailed Rasboras are moderately adaptable. Target pH 6.0–7.5, GH 3–15, KH 1–8, and temperature 22–28°C. Regular water changes of 25–30% weekly are important to maintain good water quality.

Filtration: Use a reliable hang-on or canister filter providing moderate flow. This species tolerates mild current and benefits from well-oxygenated water.

Feeding: Feed twice daily with a quality flake or micro-pellet as the staple diet. Supplement regularly with live or frozen foods such as daphnia, brine shrimp, and bloodworms to encourage good coloration and conditioning for breeding.

Social Behavior: Keep in schools of at least six. Larger groups of ten or more produce the best schooling behavior. Fully peaceful and compatible with most community fish of similar or larger size.

Breeding: Egg scatterers that spawn among fine-leaved plants. Remove adults after spawning as they will consume eggs. Fry are small and require infusoria or micro-foods initially.

Health: Robust and generally disease-resistant when kept in clean, stable water. Watch for signs of ich or fin rot in suboptimal conditions.