Identification:
Small-sized fish, with a high body, slightly humped, and laterally compressed. Possesses two pairs of barbels of approximately equal length. The mouth is directed forward. The lips are thick. The snout is short. The eyes are relatively large. The interorbital space (distance between the eyes) is wide. The dorsal fin originates anterior to the origin of the pelvic fins. The anus is positioned anterior to the origin of the anal fin. The terminal unbranched ray of the dorsal and anal fins is ossified into a strong, spiny structure with posterior serrations. The back and flanks are grayish-brown, while the abdomen is grayish-yellow. Each scale has a dark spot, resulting in 12-13 dark stripes parallel to the lateral line. The fins are gray with paler bases.
Biology and Ecology:
This fish inhabits the bottom layer of water bodies, favoring areas with a mixture of sand and mud substrate and abundant aquatic vegetation. It exhibits poor adaptability to environmental changes, unable to withstand harsh conditions such as stagnant or turbid water and low oxygen levels. It is an omnivore, feeding on benthic invertebrates, snails, freshwater mussels, oligochaete worms, midge larvae, zooplankton, and shrimp. Additionally, it consumes young plants, soft-seeded grains, and organic detritus accumulated on the bottom.
The fish grows rapidly, reaching a length of 150mm in one year, 240mm in two years, 368mm in three years, 475mm in four years, 580mm in five years, and 660mm in six years. The largest individuals can reach 10-15 kg. It reaches sexual maturity at the age of two years, with a length of 24 cm or more. Spawning activity is most frequent in the 3-4 year old age group. A female fish measuring 72 cm in length and weighing 5100 g can contain 78,500 eggs, while a female measuring 100 cm in length and weighing 7,000 g can contain 85,400 eggs. The spawning season is from April to May. The fish is a demersal spawner, laying adhesive eggs. Spawning grounds are typically located in stream crevices, at the interface of water sources, with abundant aquatic plants and reeds.
Distribution:
Within Vietnam:
Rivers and streams in the northern mountainous regions, including: Ha Giang, Tuyen Quang (Lo – Gam River), Bac Kan (Nang River – Ba Be Lake), Yen Bai, Phu Tho (Thao River, Thac Ba Lake), Hoa Binh (Da River, Hoa Binh Lake), Lang Son (Trung River – Huu Lung area), Thai Nguyen, Bac Giang (Cau River, Thuong River).
Worldwide:
China (Xi River – Guangxi Province).
Value:
It is a characteristic species of the rivers and streams in the mountainous regions of northern Vietnam and the Xi River (China). The fish exhibits rapid growth, has tasty flesh, and is favored by local people. The production of this fish in the past was relatively high in some areas such as Ba Be Lake (Bac Kan), Lo – Gam River (Tuyen Quang), and Da River (Hoa Binh), contributing significantly to the local food supply.
Status:
The fish is currently experiencing a severe decline due to habitat loss exceeding 80%, and its production has decreased rapidly in the last 10 years. The species is almost extinct in natural waters. In Ba Be Lake (Bac Kan), the fish accounted for 3.5% of the fish production in 1962 and 1.5-2.5% in 1975 (Nguyen Van Hao, 1975), but is no longer present today (Nguyen Van Hao et al., 1999). The fish is no longer observed in the Da River (Nguyen Huu Duc, Nguyen Van Hao et al., 2001).
Ranking:
EW (Extinct in the Wild)
Conservation Measures:
The species was included in the Vietnam Red Data Book (1992, 2000) with an assessed threat level of E (Extinct in the Wild) and in the list of species needing protection by the fisheries sector before 1996. However, to date, there have been no conservation measures for this species in key areas. If it is found, exploitation should be strictly prohibited for 8-10 years. It is necessary to collect, preserve, and conserve it in Ba Be Lake (Bac Kan) and the Gam River area in the two districts of Na Hang – Tuyen Quang and Bac Me – Ha Giang. Research should focus on bringing the fish to aquaculture ponds and creating breeding stock to replenish populations and restore resources in natural waters.