Denison's Barb (Sahyadria denisonii)

Sahyadria denisonii, Denison's Barb (also called the Roseline Shark or Red-Line Torpedo Barb), is one of the most spectacular medium-sized freshwater fish in the aquarium hobby and is endemic to the fast-flowing hill streams of the Western Ghats in Kerala and Karnataka states of India. The species is listed as Endangered on the IUCN Red List due to over-collection and habitat destruction, though captive-bred specimens now dominate the trade.

The body form is streamlined and torpedo-shaped, perfectly suited to fast-flowing river currents. The colouration is striking and complex: a bright silver body with a bold red stripe running from the tip of the snout through the eye to the tail, a parallel black stripe below, a black and yellow-green pattern on the caudal fin, and a vivid green-yellow dorsal fin. The overall effect is one of the most precisely patterned freshwater fish available.

Denison's Barbs grow to approximately 13–15 cm and are active, fast-swimming schooling fish that require a large aquarium with good open swimming space. They are peaceful toward other species but need the open current swimming lanes that characterise their natural rapid stream habitat.

The species is difficult to breed in captivity — most captive-bred specimens are produced in commercial fish farms in India using hormone injection, as natural breeding is rarely achieved in aquariums. This has reduced wild collection pressure significantly.

Tank Setup: A minimum 250-litre aquarium (150 cm long) for a school of six. Strong water flow with a powerhead or circulation pump — this is a fast-water species. Open mid-water swimming lanes, planted edges and background with robust plants (Vallisneria, Anubias), and smooth rock decor. An excellent lid — exceptional jumpers.

Water Parameters: Temperature 15–25°C; pH 6.5–7.8; GH 5–20 °dH; KH 3–10 °dH. Prefers cooler water than typical tropical fish — reflecting hill stream origins. Avoids warm tropical conditions. Excellent oxygenation is critical.

Feeding: Omnivore. Accepts quality flake, pellets, frozen bloodworm, brine shrimp, Daphnia, and blanched vegetables. Fast swimmers that compete aggressively at feeding time — ensure enough food for all. Feed two to three times daily.

Tank Mates: Best with other medium to large, robust community fish: large barbs, medium to large tetras, rainbowfish, larger danios, loaches, and corydoras. Avoid small nano fish and very slow-moving species. Not suitable for warmer Discus setups.

Behaviour: Fast, active mid-water schooling fish. Groups of 6+ school attractively in fast-moving water. Non-aggressive toward other species but energetic and may startle slow fish.

Health: Hardy but temperature sensitive — avoid sustained temperatures above 25°C. Susceptible to ich in warm, poor-quality water. Regular 25–30% water changes with good oxygenation prevent most issues.