Roseline Shark (2.5”)

Scientific Name

Dawkinsia denisonii
(also known in older classification as Puntius denisonii or Sahyadria denisonii).

Maximum Size and Lifespan

• Size: Typically 9–12 cm (3.5–4.7 in), but can reach up to 15 cm (6 in) in larger systems.

• Lifespan: Averages around 5 years in captivity with good care.

Aquarium Size, Water Changes & Care

• Minimum tank size: 40 gallons (200 L) or larger to provide open swimming room. 55+ gallons is recommended for a large group/community setup

• Water changes: 25–30% weekly water change is ideal to maintain quality.

• Water parameters:

  • Temperature: 70–80 °F)

  • pH: 6.5–7.8
    

• Filtration and flow: Strong filtration and a moderate to fast current are preferred, as these fish come from oxygen-rich rivers.

• Aquascaping: A mix of open swimming space with background planting and smooth substrates like sand; floating plants can help mimic natural shading.

Tankmates

Roseline Sharks are active, shoaling fish and should be kept in groups of at least six to reduce stress.

• Good companions: Rainbowfish, medium sized barbs, medium tetras, danios, gouramis, corydoras, and loaches. 

• Avoid: Very small, timid, or long-finned species which may be harassed or stressed.

Diet

They are omnivores with a varied appetite:

• Staples: High-quality flakes and pellets.

• Protein foods: Frozen bloodworms and brine shrimp

• Vegetable matter: Spirulina based foods

Natural Environment

Roseline Sharks come from the Western Ghats of India, inhabiting fast-flowing, clear, oxygen-rich hill streams with rocky bottoms and aquatic vegetation. They shoal in groups among plants and submerged rocks. Habitat destruction and over-collection have endangered wild populations, though many aquarium specimens today are farm-bred.

Breeding

Breeding is rare and difficult in home aquaria.

• In the wild, they spawn seasonally during the monsoon.

• In captivity, breeders sometimes mimic monsoon conditions with cooler temperatures, heavier water changes, and increased current.

• Success is limited, and most available fish are commercially bred rather than hobbyist-bred.