Sterlet (Acipenser ruthenus)

Sterlet  (Acipenser ruthenus)

This is one of the smaller species of sturgeon, it is a common Eurasione species and is an angling species all over the world and kept domestically in the UK and Europe. It is also grown for its caviar, for eating and for isinglass (a substance obtained from the swimbladders of fish (especially Beluga sturgeon). It is a form of collagen used mainly for the clarification of wine and beer.)

The Sterlet can reach weights of up to 16kg and grow to 1-1.25m, however it is relatively slow growing. It has variations of colour from grey through to earthy brown, although the ventral or underside is usually of a yellowish hue. There is also an albino variation that has no pigment in the skin and is a pale yellowy colour all over, with the same coloured eyes. It's large number of whitish lateral skutes, fringed barbels and elongated, narrow snout distinguish it from other European species.

This sturgeon is a freshwater species and inhabits rivers that flow into the following seas: Caspian, Black, Azov, Baltic, White, Barents, Kara, and inhabits both the Black and Caspian seas, and ascends rivers to a greater distance from the sea than any of the other sturgeons. It is less tolerant of salt than other species but can be treated with a solute at the same levels used for koi. Being a bethnic (bottom) feeder it's main diet in the wild consists of small crustaceans, worms, and insect larvae.

The sterlet commonly reaches the age of 22 to 25 years. It is late to reach sexual maturity, in common with other species. Typically 3-7yrs in males and 5-12 yrs in females.

If kept in captivity they require relatively large ponds with good water conditions, and may get entangled in plants such as blanketweed, as with other species they cannot swim backwards. They are friendly fish and can become hand tame. Sterlets require specialist food such as sterlet sticks, as they are unable to digest the vegetable proteins usually found in commercial fish foods. They need a high protein diet. Their smaller maximum size makes them the best choice for the hobbyist wishing to have a sturgeon in their pond. It tends to produce more mucus than other species because of this it is obviously very slippery, therefore extra care should be taken when handling them, using a net is advised. If you need to transport your Sterlet for whatever reason, adequate water should be provided as the extra mucus may thicken the water and cause distress.