Filament barb (Dawkinsia filamentosa) care guide

Group
Freshwater fish
Other names
Black-spot barb, Blackspot barb, Filament barb, Mahecola barb (trade misnomer), Puntius filamentosus
Family
Cyprinidae (Smiliogastrinae, small barbs)
Origin
Western Ghats of southern India (Kerala, Tamil Nadu and possibly southern Karnataka); mainly coastal lowland floodplains, rivers, estuaries, marshes and reservoirs.
Water
freshwater
Maximum size
12 cm
Temperature
20–25°C
pH
6–7
Hardness
Soft to moderately hard, 2–15 dGH
Minimum tank
162 litres
Care level
beginner
Temperament
peaceful

Care

The filament barb is a lively, fairly large shoaling barb and should be kept in a group of at least 8–10; males sort themselves into a pecking order, and a group spreads out any squabbling. It is an active swimmer and grows to about 12 cm, so it needs a tank with a base of at least 120 × 45 cm (around 162 litres) and plenty of open swimming space. Decorate the tank like a flowing stream: sand and fine gravel with water-worn rocks and pebbles of various sizes, some driftwood, and hardy plants such as Java fern (Microsorum), Bolbitis or Anubias tied to the decor. Good water movement and plenty of oxygen are important. It does well at about 20–25 °C, pH 6–7 and 2–15 dGH. It is not hard to keep, but it comes from clean water and does not tolerate a build-up of waste, so filter well and change 30–50% of the water each week. Adults are silvery with a reddish tail and a black blotch near the tail base; the tail lobes have dark bands near the tips. Young fish are plain with black spots and colour up from about three months old. Mature fish, especially males, may grow long filaments from the dorsal fin, though these vary between populations and can be lost outside the breeding season. Males colour up more strongly and grow small white tubercles on the head when spawning; females grow slightly larger, are heavier-bodied and duller. It has long been sold under the wrong name 'mahecola barb' (true Puntius mahecola is a different, smaller silvery fish). It was moved from Puntius into the new genus Dawkinsia, named after Richard Dawkins, in 2012. Similar species include D. assimilis and D. rohani. The IUCN lists it as Least Concern (assessed 2020). Sources: Seriously Fish (seriouslyfish.com/species/dawkinsia-filamentosa/); FishBase (fishbase.se/summary/Dawkinsia-filamentosa.html); Wikipedia (en.wikipedia.org/wiki/Dawkinsiafilamentosa). Checked October 2026.

Diet

Probably an omnivorous forager in the wild. In the aquarium give a balanced, varied diet: good-quality dried flakes and granules alongside regular meals of small live and frozen foods such as bloodworm, Daphnia and Artemia.

Breeding

An egg-scatterer that gives no parental care and will eat its eggs. Use a separate, dimly lit spawning tank with a mesh base (so eggs fall out of reach) or a mass of fine-leaved plants or spawning mops. Slightly acidic to neutral water at the warmer end of the range helps. Introduce a well-conditioned pair or small group and remove the adults after spawning. The eggs hatch in 24–48 hours and the fry swim freely about a day later. Feed microscopic foods such as infusoria first, then microworm and newly hatched brine shrimp.

Compatibility and tank mates

Peaceful but bold and fast-moving, so it suits a larger community of similar-sized, robust fish from flowing water: other medium-sized barbs and cyprinids, loaches such as hillstream or botiine loaches, and similar riverine species. It may unsettle very small, slow or shy fish and can outcompete them for food.

Last updated 5 October 2026. Community-edited care guide on Aquatic-Auctions.

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