Aspiolucius esocinus - The Asp
The asp is considered a river inhabitant. It is endemic to Central Asia. A fairly large fish, reaching lengths of 60-70 cm and a body weight of up to 3-3.5 kg. It prefers riverbeds, occasionally found in lakes. It inhabits currents with murky water, and in reservoirs, it stays in the river mouth areas where the water is turbid.
Its biology is poorly studied. It reaches sexual maturity at the age of 6-7 years when it attains a body length of 45-50 cm. Spawning occurs in February-March when the water temperature reaches 5-10°C, and it does not happen every year. The eggs are laid in fast currents. Fecundity ranges from 22,000 to 200,000 eggs. The diameter of the eggs is 1.2-2.1 mm.
A predator, it primarily feeds on fish. It is a timid fish that leads a solitary lifestyle. Fish aged 3-5 years dominate the catches. In Kyrgyzstan, it inhabits the basin of the Naryn River, below the cascade of reservoirs. In the early years after the Toktogul Reservoir was filled, it was also found there. Subsequently, its numbers decreased, and it became very rarely caught.
The name "esocinus" was given to this species due to its elongated and flattened head, resembling that of a pike. This fish is diurnal, loves light and space, and retreats to deeper waters at night. It is timid and leads a solitary lifestyle.
The asp is listed in the Red Books of all countries through which the Syr Darya River (known as Naryn in its upper reaches) and the Amu Darya River flow.
Fish