Red-tailed Rasbora

The red-tailed rasbora takes its scientific name from Bueng Boraphet, a lake in central Thailand. Its slender, elongated body is silvery gold; above the dark stripe running from behind the gill cover to the caudal peduncle there is a thin, bright golden line. The red patch at the base of the tail fin is the species' most easily recognized mark.

It grows to about 6 cm. It is easy to feed, adapts to a wide range of water values and is peaceful, which makes it a suitable rasbora for beginners too. As a large school it creates a lively, harmonious display in the middle of the aquarium.

It lives in the lowlands of Indochina, in vegetated lakes, swamps, canals and the waters of rice paddies. The water is usually still or slow-flowing, soft and slightly acidic; in the rainy season it spreads into flooded areas.

• Volume: at least 60 liters and 60 cm in length for a school of 8–10.
• Water: 23–26°C, pH 6–7.5, soft to moderately hard water.
• Layout: plenty of plants along the sides, open swimming space in the middle; a dark substrate brings out the colors.
• Flow: gentle to moderate.
• Lid: it may jump during sudden escapes; use a lid.

Omnivorous. Flakes and small granules can be the staple; vary the diet with frozen brine shrimp, daphnia, mosquito larvae and bloodworms. Its red tones become more pronounced with a varied diet.

Peaceful, active and social. It swims as a school in the middle layer and occasionally rises to the surface. There are small chases within the species, but they are harmless.

Good companions: other rasboras, small and medium-sized tetras, corydoras, kuhli loaches, otocinclus, dwarf gouramis, shrimp.

Avoid: large predatory fish and aggressive cichlids.

At least 8, ideally 12 or more individuals. In a large school the fish are bolder and show their colors better. Kept in small numbers they become shy and retreat among the plants. The male-to-female ratio is not important.

It scatters its eggs among fine-leaved plants and moss; there is no parental care and the adults eat the eggs. For breeding, a separate aquarium with soft, slightly acidic water and dense fine-leaved plants or an egg grid is used. The adults are removed after spawning; the fry start on infusoria and then take newly hatched brine shrimp.

A hardy species. Poor water quality and temperature swings can lead to white spot and bacterial fin rot. A 25% weekly water change and a short quarantine for new fish are sufficient.

Males are slimmer and their colors, especially the red at the base of the tail and the golden line above the stripe, are more pronounced. Females have a fuller belly and are slightly larger.