Sterlet - Acipenser ruthenus

The sterlet belongs to the somewhat smaller sturgeons, it grows to "only" 1.20 m long and weighs four kg and therefore also fits into medium-sized garden ponds. Acipenser ruthenus comes from Russia. With its bizarre appearance, the bony fish looks like a remnant from prehistoric times. The sterlet is a lively, agile and prima observable inhabitant for the garden pond. This interesting pond fish is dark brown to grayish brown in coloration, with a lighter belly. Its bright bony shields are arranged in prominent rows, and the body is elongated and spindle-shaped. The typically shaped sturgeon snout tapers to a point and bears pairs of barbels.

Adult sterlets are found in the wild predominantly in stream-rich sections in tributaries to the Black Sea, the Sea of Azov and the Caspian Sea. It is a pure freshwater fish and rarely strays into brackish water. Sterlets have also been successfully reintroduced into the Danube and Isar rivers. In the wild, many sterlet stocks are considered endangered - our sterlets are therefore all from responsible breeding.

Sturgeons are already quite large when they become sexually mature - this can take 8 years. The Russian sterlet migrates many kilometers to its upstream spawning grounds when water levels are high. At low water levels, sterlets may spawn without migrating. This may allow the sterlet to reproduce in the garden pond, although this is unlikely. For spawning, the fish prefer gravelly substrate in a water depth of 2 m or more and a very strong current, which is rather difficult to create in the pond.

The sterlet is a predatory fish that likes to forage on the bottom and in the pond mud. There sterlets look for worms and insect larvae, insects, crustaceans, snails and so on. They also eat fish fry and sometimes smaller fish, depending on their size. Sterlets are slow eaters and need feeding in the garden pond with a sinking sturgeon food. With a little patience, the sterlet can become tame, and then they will gladly let you feed them from your hand. Pond fish food floating on the surface can cause the sterlet to swallow a lot of air, which can cause problems. Sterlets should not be socialized with voracious eating fish that need food floating on top.

The sterlet is a very active swimmer and moves around the pond all day. This is also true in winter - the sterlet does not hibernate and can severely disturb fish that are in hibernation. That is why, for example, koi are not good pond mates for sturgeons. Sterlets are solitary animals and can therefore live in a pond as a single specimen without any problems.

A pond for the active sterlet needs at least 10 cubic meters of water volume and a length of at least 15 meters. The pond must be at least 1.50 meters deep. In summer, oxygen-hungry sturgeon may retreat to cooler water layers where even more oxygen is dissolved. For this reason, a sturgeon pond also needs a good supply of oxygen through a water feature, an air pump or an oxydator for ponds. If you want to see the more bottom-oriented sterlets in the pond more often, you should create terraces of different heights in the pond, which are covered with a muddy or loamy substrate. The sterlet likes to burrow in this soft substrate and dig for food there.

Sturgeons are unable to maneuver backwards and therefore must not live in ponds that are too densely planted. They can otherwise become entangled in the dense stands of aquatic plants and even die. For young sturgeons, filamentous algae can also become a deadly trap; they must be controlled in the sturgeon pond and removed if necessary.