Caviar off their coasts. Beluga caviar is prized for its soft, extremely large (pea-size) eggs. It can range in color from pale silver-gray to black. It is followed by the small golden sterlet caviar which is rare and was once reserved for Russian, Iranian and Austrian royalty. Next in quality is the medium-sized, light brown to rich brown Ossetra, also known as Russian caviar. Others in the quality ranking are the gray sevruga caviar, the Chinese Kaluga caviar, and the American osetra. The Siberian variety with black beads is similar to sevruga and is popular because of its reduced (5 years)
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.