Denison barb (roseline shark)
Sahyadria denisonii
intermediate careOverview
The Denison barb (Sahyadria denisonii), sold as the roseline shark or red-line torpedo barb, is a sleek, silver, torpedo-shaped fish marked with a bold black stripe and a flash of red along the head. It comes from fast, cool hill streams in the Western Ghats of India, and it brings that energy to the aquarium: it’s a powerful, restless shoaler that needs serious space. Beautiful and hardy, but not a fish to underestimate on tank size.
Tank & water
Adults reach 11–15 cm and swim hard all day, so a group needs a minimum of 240 litres (60 gallons) with a long footprint.
- Space and flow: length and open swimming room are essential, along with brisk current from a strong filter and good oxygenation.
- Cooler water: aim for 18–25 °C — they suit the cool end of tropical. A heater keeps winter lows stable rather than pushing them warm.
- Water quality: pH 6.5–7.8, well-filtered and clean. Cycle fully before stocking.
- A lid: they are fast and can jump — cover the tank.
Feeding
An unfussy omnivore, the Denison barb eats quality flakes and sinking pellets from the fish food range and relishes live and frozen foods — bloodworm, brine shrimp, daphnia — plus some vegetable matter and algae. Their fast metabolism means they are always hungry; feed generously but keep the water clean.
Tankmates
Best kept with robust, active fish that can hold their own: other Denison barbs, larger barbs and rainbowfishes, bigger tetras, and sturdy bottom-dwellers like bristlenose plecos. Avoid tiny, slow or long-finned fish that will be nipped or outcompeted. Always keep a shoal of six or more.
Plan around their size with our best large aquarium guide and check stocking with how many fish in an aquarium.
Common mistakes to avoid
- Keeping them in too small a tank
- Small groups that turn nervous and nippy
- Housing them with tiny or timid tankmates
- Keeping them too warm with weak flow
Denison barb (roseline shark) — frequently asked questions
How many Denison barbs should I keep?
Six or more. Kept singly or in small numbers they become nervous and nippy, and can harass other fish. In a proper shoal they settle, colour up and behave far better. That group of large, fast fish is why they need a big tank.
Do Denison barbs need cool water?
They prefer the cooler end of tropical, roughly 18–25 °C, reflecting their fast-flowing hill-stream origins in India. They tolerate warmer water short-term but do best kept cooler and well-oxygenated with good flow.
Are Denison barbs aggressive?
They are semi-aggressive and boisterous rather than truly nasty. They can nip fins and outcompete slow fish at feeding, especially in small groups. In a large tank, in a good shoal, with robust tankmates, they are generally peaceful.
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