cm. It is quite variable in coloration, but usually has a yellowish ventral side. It is distinguishable from other European species of sturgeons by the presence of a great number of whitish lateral scutes, fringed barbels, and an elongated and narrow snout, highly variable in length. Feeding habits The sterlet's main source of food is benthic organisms; they commonly feed on crustaceans, worms, and insect larvae. Life history The sterlet commonly reaches the age of 22 to 25 years. Males reach sexual maturity at 3–7 years old and females at 4–12 years old. Spawning occurs from the middle of April to the beginning of June. Females may lay from 15,000–44,000 eggs, at water temperatures preferably 12–17 °C (54–63 °F). As pond fish Sterlets require relatively large ponds with good water conditions, and may get entangled in plants such as blanketweed. They may require special food such as sterlet sticks, as they are unable to digest the vegetable proteins usually found in commercial fish foods. As food In Russia, it is held in high esteem on account of its excellent flesh, contributing also to the best kinds of caviar and isinglass. History in the Danube The sterlet (Acipenser ruthenus'' in Linnaeus' classification) is the last of the five native sturgeon species inhabiting the Middle and Upper Danube River. Its population has dropped significantly, mainly due to the degradation of main habitats, spawning grounds and foraging grounds. References Freshwater fish of Europe Fish of Europe Fish of the Black Sea Fish of Central Asia Fish of Russia Fish described in 1758 Acipenser Taxa named by Carl Linnaeus