Mascara Barb (Dawkinsia assimilis)

Common Name

Mascara Barb
Dawkinsia assimilis

A striking Western Ghats barb named for the dark mascara mark beneath the eye. When a group gets moving the body flashes copper, gold, and emerald with red in the fins, a look that photos rarely capture.

Origin and Habitat

Endemic to the southern Western Ghats of India, with records from the Netravati, Chalakudy, and Kallada river basins in Karnataka and Kerala. These fishes occur in mixed habitats from slow edge areas over mud to clear, rocky runs with moderate to fast flow. Water is well oxygenated and seasonal monsoon cycles shape current and clarity.

Temperature and Water Conditions

A steady aquarium range of 22 to 26 °C (72 to 79 °F) suits long-term care.

• Prioritize high dissolved oxygen, reliable filtration, and regular water changes.
• Keep ammonia and nitrite at zero and nitrate low.
• Stable conditions are far more important than chasing exact parameters.

Appearance and Size

Adults show a dark eye stripe, a caudal peduncle blotch, and red to orange accents in fins, with males developing more intense iridescence and often longer dorsal rays. Maximum size is reported around 11.2 cm standard length (about 4.4 in SL). In home aquaria this typically corresponds to roughly 12–13 cm total length (about 4.7–5.1 in TL).

Diet in the Wild

Like many Dawkinsia, this species is an opportunistic forager that takes small worms, insects, crustaceans, and some plant material and detritus while moving in the water column and near the bottom.

Feeding in Captivity

Offer a rotation of quality flakes and pellets sized for barbs, plus frequent small servings of live or frozen foods such as daphnia, baby brine shrimp, chopped bloodworms, and mysis.

• Two to three modest feedings daily keep energy high and color strong while minimizing waste.

Behavior and Tank Setup

A fast-moving, social barb that should be kept in a real group.

• Plan for at least 8–10 individuals so sparring stays within the group and the schooling display comes alive.
• Provide length to run — a tank with a footprint around 120 × 45 cm (47 × 18 in) or larger.
• Use strong filtration and supplemental aeration to keep oxygen high.

Plant compatibility: Many aquarists keep Dawkinsia in planted tanks, but softer-leaved species can be nibbled. Favor sturdy plants such as Anubias, Java fern, Bolbitis, and tougher rooted choices like Vallisneria. Keep a vegetable component in the diet and maintain good grazing options to reduce nibbling.

Breeding

A free-spawning egg scatterer.

• Condition a group with varied live and frozen foods.
• Spawns are often triggered after large water changes with slightly cooler water (simulating rains), very clean, well-oxygenated conditions, and a noticeable increase in flow.
• Provide fine plants or spawning mops and pockets of larger gravel or marbles so adhesive eggs fall out of reach.
• Remove adults after spawning to improve yield.
• Close congeners suggest these barbs can take a year or more to reach full sexual maturity.

Quick Facts

• Scientific name: Dawkinsia assimilis
• Common name: Mascara Barb
• Origin: Southern Western Ghats, India (Netravati, Chalakudy, and Kallada basins)
• Adult size: ~11.2 cm SL (~4.4 in SL), often 12–13 cm TL (~4.7–5.1 in TL)
• Temperature: 22–26 °C (72–79 °F)
• pH and hardness: Adaptable within typical community ranges when stable and well oxygenated
• Temperament: Active, social barb for groups
• Diet: Omnivorous forager; accepts quality prepared foods and small live/frozen fare
• Recommended footprint: ~120 × 45 cm (~47 × 18 in) or larger
• Breeding: Egg scatterer; fine plants or mops plus coarse substrate pockets help protect eggs

Tropical Fish Co. Notes

Jonny and Chris really love these swimming rainbows of iridescence. They look pretty in pictures but in person they are truly breathtaking. Give them space, flow, and hardy planting and they turn a long tank into a living river.