Puntius filamentosus, the Blackspot Barb, is one of the larger schooling barbs from South Asia, growing to around 15 cm in well-maintained aquariums. It is native to rivers, streams, and reservoirs in southern India and Sri Lanka, where it forms large shoals in open water. Adult males are particularly impressive: the dorsal fin develops greatly elongated filamentous rays, and a bold black blotch on the shoulder contrasts sharply with the otherwise silvery-olive body.
Despite its size, this barb is entirely peaceful and does not trouble even long-finned tankmates. It requires spacious accommodation — a tank of at least 200 litres with a strong filter and plenty of open swimming space is essential. Groups of eight or more are needed for natural schooling behaviour, and the spectacle of a large shoal in motion is one of the hobby's more arresting sights.
Breeding in captivity is well-documented. Females swell noticeably with eggs when conditioned on live and frozen food. A large, slightly cooled spawning tank furnished with fine-leaved plants produces best results; adults must be removed once spawning is complete as they will consume eggs.