Chocolate Mahseer
Why in News?
Chocolate Mahseer is in the news because Sikkim’s Chief Minister Prem Singh Tamang released it into the Rangeet River during the Chirbirey River Fest as part of an indigenous-fish conservation and fish-ranching initiative.
Taxonomy & Scientific Details
- Scientific Name: Neolissochilus hexagonolepis.
- Family: Belongs to the Cyprinidae family, which encompasses carps, barbs, and related fish species.
- Local Nomenclature: It is widely known as 'Khasaw' in Khasi, 'Na•rong' or 'Na-rang' in Garo (Meghalaya), and 'Katley' in Sikkim.
Habitat & Geographical Distribution
- Northeastern India: It thrives in almost all major rivers and hill streams of Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, and Tripura.
- Global Presence: Beyond India, it is native to Nepal, Bangladesh, Myanmar, Thailand, Malaysia, and Sumatra (Indonesia).
- Water Preference: It inhabits cool, clear, fast-flowing, and oxygen-rich mountain streams and rivers featuring rocky, pebbly, or gravelly bottoms. It can comfortably adapt to high gradients up to 1,500 meters above sea level.
Physical Characteristics & Anatomy
- Coloration & Scale appearance: Known for its striking olive-green to deep chocolate coloration on its back, with a coppery hue on the scales above the lateral line and a silvery-white belly.
- Size & Weight: It is a large freshwater game fish that can grow up to 120 cm in length and weigh as much as 11 kilograms.
- Sexual Dimorphism: Females of this species grow larger in size than males within the same age bracket.
- Agility: Equipped with highly powerful pectoral and dorsal fins, it possesses a unique ability to swiftly swim against fierce river currents, making it exceptionally strong.
Ecological & Economic Importance
- Bio-indicator: It serves as an excellent indicator of a healthy river ecosystem; its presence signals clean, well-oxygenated water.
- Angling & Tourism: Because of its incredible strength, it is a highly prized catch for recreational anglers and plays a vital role in local eco-tourism.
- Aquaculture Potential: Unlike some sensitive mahseer species, the Chocolate Mahseer is highly adaptable to captive rearing and pond culture, making it an ideal candidate for hill aquaculture diversification.
Conservation Status & Threats
- IUCN Red List: Classified as Near Threatened.
- Primary Threats: Populations are rapidly declining due to severe habitat degradation, water pollution, environmental changes, and overfishing.
- Unethical Fishing: In several areas, illegal and destructive practices like dynamite blasting and poisoning rivers have heavily depleted their numbers.
- Protection Measures: In response, states like Meghalaya have set up over 113 community-based fish sanctuaries to protect natural breeding grounds and promote scientific river-stocking programs.
