Filament Barb - Dawkinsia Filamentosa

Filament Barb | A Majestic and Rare Schooling Fish From the Rivers of India

The Filament Barb (Dawkinsia filamentosa) is one of the most impressive and visually commanding barbs available in the freshwater aquarium hobby. Native to the fast-flowing, well-oxygenated rivers and hill streams of the Western Ghats in southern India — sharing much of its range with its close relative the Mascara Barb — this large, deep-bodied barb is prized for its extraordinary finnage and striking colouration. Breeding males develop dramatically elongated, filament-like extensions on the dorsal fin that trail behind them as they swim — the defining feature that gives this species its name — alongside vivid red-orange fin colouration, a bold black lateral spot, and a metallic silver-gold body that shimmers brilliantly under good lighting.

Still relatively uncommon in the hobby outside of dedicated enthusiasts, the Filament Barb is a genuine showstopper in a large, well-planted river-style aquarium.

Filament Barb Care Guide

Care at a Glance

• Scientific name: Dawkinsia filamentosa
• Also known as: Filament Barb, Blackspot Barb, Filamentous Barb
• Origin: Western Ghats, southern India — Kerala and Tamil Nadu
• Adult size: up to 6 inches (15 cm)
• Minimum tank size: 75 gallons — longer tanks strongly preferred; minimum 47 inches (120 cm) frontage recommended
• Temperature: 68–79°F (20–26°C) — a cooler water species that prefers the lower end of the tropical range
• pH: 6.0–7.5
• Hardness: soft to moderately hard water
• Strong filtration and high oxygenation essential
• Best kept in groups of 6 or more
• Lifespan: 5–8 years with good care

Filament Barb Tank Setup

A spacious aquarium with strong water flow, excellent oxygenation, and plenty of open swimming space suits these fish perfectly — reflecting their natural fast-moving hill stream habitat in the Western Ghats. Fine sand or smooth gravel substrate, smooth rocks, boulders, driftwood, and hardy plants such as Java Fern, Anubias, and Vallisneria provide structure and cover while leaving generous open water for the school to move freely. A filter providing 4–5 times the tank volume per hour is recommended to maintain the well-oxygenated, clean conditions this species demands.

Feeding Your Filament Barbs

Omnivores with a healthy appetite. A high quality flake or pellet forms an excellent staple diet, supplemented regularly with frozen or live foods such as bloodworm, brine shrimp, daphnia, and small insects. A varied, protein-rich diet and colour-enhancing foods will bring out the full intensity of the red-orange fin colouration in males and encourage the development of the dramatic dorsal filaments.

How Many Filament Barbs Should You Keep?

As a true schooling species, Filament Barbs should always be kept in groups of 6 or more. In a proper school, males will display competitively — fanning their extraordinary filament fins, intensifying their colouration, and chasing one another in a constantly dynamic and impressive show. A mixed sex group produces the most natural and visually rewarding behaviour.

Filament Barb Tank Mates

• Other large, active barbs such as Denison Barbs and Mascara Barbs
• Rainbowfish and similarly active, large schooling fish
• Larger gouramis and peaceful medium to large community fish
• Loaches and robust bottom dwellers
• Avoid small, slow-moving, or delicately finned fish that may be stressed by their boisterous activity
• Avoid very small fish that may be outcompeted for food or inadvertently harassed