Caviar sturgeon from the Sea of Azov began reaching the tables of aristocratic and noble Byzantine Greeks in the 10th century, after the commencement of large-scale trading between the Byzantine Empire and Kievan Rus'. The main types of caviar are Beluga, Sterlet, Kaluga hybrid, American osetra, Ossetra, Siberian sturgeon and Sevruga. The rarest and costliest is from beluga sturgeon that swim in the Caspian Sea, which is bordered by Iran, Kazakhstan, Russia, Turkmenistan, and Azerbaijan. Wild caviar production was suspended in Russia between 2008 and 2011 to allow wild stocks to replenish. Azerbaijan and Iran also allow the fishing of sturgeon
Sterlet become self-sustaining. Today, the majority of the international trade involves sterlets from aquaculture. The sterlet's main source of food is benthic organisms; they commonly feed on crustaceans, worms, and insect larvae. 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). Sterlets require relatively large ponds with good water conditions, and may get entangled in plants such as blanketweed.