• Scientific name: Pethia nigrofasciata
• Synonyms: Puntius nigrofasciatus, Barbus nigrofasciatus, Purple-headed barb
• Common name: Black-ruby barb
• Group: Cyprinids
• Habitat: Asia; Sri Lanka (Ceylon)
• Size: 6 cm
• Biotope: Slow-flowing mountain streams of Sri Lanka.
• Social behavior: A lively, active but peaceful fish which prefers schools. Can be combined with other barbs with vertical stripes.
• Diet: Omnivorous; all types of live foods; flakes with added vegetables.
• Breeding: Easy
• Tank: Minimum 75 litres
• Population: 6-7 fish for 90 litres
• Decoration: Likes a layer of mulm on the bottom and a well-planted tank with room for swimming. Lighting should be subdued, diffused by such broad-leaved floating plants as Eichhornia and Ceratopteris. The fish become frightened in a brightly-lighted aquarium. The tank should provide hiding places.
• Temperature: 22-26 °C
• pH: 6-7
• Hardness: 1-12 NK°
• Lifespan: 3-5 years

Description: A high-backed, deep bodied fish that lacks barbels. Coloring is normally subdued, with a pinkish-grey body crossed with three to four, faint black bars. The first is located above the eye, while the last is located near the caudal peduncle. The back is usually dark copper brown. In females, the bases of the fins are predominantly black, and in males the whole dorsal fins is black. In breeding condition the males glow with an intense purplish-red coloring, and the blackish areas become deep velvety black. A group of males kept together seem to compete for the females' attention by remaining in breeding coloration for most of the time.

The male is larger and more intensely colored (and example of sexual dichromatism) while the female is fatter and does not change color during the spawning season. For breeding water should be 77-82 °F (25-28 °C) not too hard and slightly acid (to 12° dGH and pH 6). The courtship begins when the male swims around the female, spreading his fins in display and spawning occurs in the morning between the plants. If the female is reluctant, the male can get quite aggressive, so she should be able to hide. The procedure may take two hours. Remove the adults after spawning. The fry hatch in 24 hours and swim freely after a week. If the eggs are not repeatedly fertilized the problem may lie with the male. Separate the pair and feed the male a plentiful, varied diet for several weeks. The tiny fry need large amounts of infusoria and other food, and can then grow up to 1cm in the first month.