Sterlet

Fish · Last reviewed 2026-08-19

The small sturgeon that never goes to sea, the only one an ordinary angler is likely to meet, and the reason 'I caught a sturgeon' is a harder statement than it sounds.

Safety

Fish welfare — Can cause injury needing treatment

A sturgeon's body is supported by cartilage rather than bone, so lifting one vertically — by the tail, or by a grip on the head — damages internal structures in a way that is not visible and that a fish may not survive. The species is additionally at risk in its native range, where an incidentally captured fish handled badly is a loss to a declining population.

What reduces it: Support the fish horizontally and under the body, keep it in the water, minimise air exposure entirely, and use forceps or cut the line rather than working a deeply taken hook. In the Danube basin, treat every sturgeon as protected until the authority says otherwise.

Worse when:

Warm summer water in the lower rivers, where oxygen is low and a long fight is far more damaging
Deep hooking on bottom baits, which is common with this species
An angler who believes they are on a stocked water and is not

Hooks and barbs — Minor injury

The rows of bony scutes are sharp on a small fish and a sterlet is a small fish. A hand drawn along the flank of one, or a grip that slips while the fish moves, cuts readily.

What reduces it: Wet hands, support from beneath rather than gripping the flanks, and keeping the fish in the water or on a wet mat rather than against clothing.

THE STERLET IS THE STURGEON THAT STAYED IN THE RIVER, AND THAT IS WHY IT IS STILL HERE.

Every other sturgeon of the Danube and the Black Sea is anadromous: it lives in the sea and runs far up the river to spawn, which is exactly the life history that dams destroyed. The sterlet completes its whole life in fresh water. It did not need to pass the Iron Gates, so the barrages that ended the migratory species did not end this one, and it survives through much of the Danube basin where its larger relatives do not.

IT IS ALSO MUCH SMALLER. A large sterlet is a fish of well under a metre, against several metres for a beluga. It feeds on bottom invertebrates — insect larvae, crustaceans, molluscs — sucked off the bed through a small protrusible mouth, guided by four fringed barbels and by the electroreceptors in its long narrow snout.

WHICH MAKES IT THE STURGEON AN ANGLER ACTUALLY ENCOUNTERS, in three quite different circumstances that carry three quite different obligations.

AS A WILD FISH IN THE DANUBE AND ITS TRIBUTARIES, where it is a native species in decline, assessed as at risk, and protected or seasonally protected in most of the basin's jurisdictions.

AS A STOCKED FISH IN MANAGED AND COMMERCIAL WATERS across central and western Europe, where sterlet and various other sturgeons are stocked deliberately, are fished for, and are entirely legitimate quarry under the fishery's own terms. This is a large and growing part of European coarse fishing and it has nothing to do with the conservation situation in the Danube.

AND AS AN ESCAPE. Sturgeon aquaculture across Europe holds several species, including non-native ones and deliberate hybrids, and escapes into open water occur. A sturgeon in a river outside its native range is very likely one of these.

SO THE PRACTICAL PROBLEM IS NOT CATCHING ONE. IT IS KNOWING WHICH SITUATION YOU ARE IN, and that is a question about the water and its rules rather than about the fish.

Identification

FishingHQ holds no photograph of this species whose identity and licensing it can vouch for, so it is not showing one. Misidentified fish photographs teach identification wrongly, and a picture with an unchecked caption would be worse than none. The identification points below are what to look at instead.

Scientific name: Acipenser ruthenus
Family: Acipenseridae
Water: Freshwater
Conservation status: Vulnerable
Regions: Central & Eastern Europe, Northern Europe

A sturgeon: five rows of bony scutes instead of scales, a shark-like tail with a longer upper lobe, and a toothless protrusible mouth on the underside of the head with four barbels in front of it.
Sterlet specifically: a long, narrow, distinctly pointed and slightly upturned snout, noticeably more slender than in the other sturgeons of the basin.
The barbels are fringed — carrying small branching filaments — rather than smooth. This is one of the more reliable characters and it can be seen with the fish in the water.
A high count of small lateral scutes, typically well over fifty along each flank and often light-coloured, giving the side a distinctly beaded appearance that the larger-scuted species do not have.
The mouth is small and transverse, not the large crescent of a beluga.
Small: an adult sterlet is a fish of 40–60 cm, which by itself separates it from any mature migratory sturgeon.
A STERLET-LIKE FISH IS NOT NECESSARILY A STERLET. Sturgeons hybridise readily, aquaculture holds several species and deliberate hybrids, and escapes occur — and a juvenile of a large migratory species is also sterlet-sized.
So snout shape and barbel fringing are the characters to look at, and a fish that does not clearly key out should be treated as a protected species and released rather than identified optimistically.

Size

Typical: 30–50 cm
Large: 60–80 cm

Exceptional: FishBase records a maximum around 125 cm, which is exceptional and historical rather than a size anyone should expect

Lifecycle and reproduction

Matures far earlier than the migratory sturgeons — commonly at three to seven years — and lives to perhaps twenty to thirty. That earlier maturity is the second reason, after its freshwater life history, that it has persisted where the others have not: a generation turns over in years rather than in decades, so a population can respond to protection within a human timescale.

Spawns in spring in fast water over clean gravel and stone in the main river and its larger tributaries, moving upstream to do so but staying within fresh water throughout. Adhesive eggs on clean gravel, which is the requirement that river regulation, dredging and sedimentation interfere with even where the fish itself is unimpeded.

Feeding and senses

A bottom feeder on invertebrates — chironomid and other insect larvae, crustaceans, molluscs and worms — taken by sucking through the protrusible mouth after the barbels have located them. Unlike the beluga it is not a fish predator, and the small transverse mouth reflects that.

Barbels carrying taste and touch receptors are swept over the bed ahead of the mouth, and the snout carries ampullary electroreceptors that detect buried prey. Vision is comparatively unimportant, which suits a fish living on the bed of a large turbid river and feeding largely at night.

Through the year

Moves upstream to spawn in spring and drops back afterwards, and in the larger rivers congregates in deeper reaches to overwinter. Feeding activity falls sharply in cold water, which is when the wintering concentrations make the species most vulnerable to being taken in numbers.

Distribution

Native to the rivers of the Black Sea, Azov and Caspian basins — the Danube above all, together with the Dnieper, Don, Volga and Ural — and to some rivers of the Siberian Arctic drainage. Widely stocked and held in aquaculture well outside that native range, so its presence in a given water says nothing about whether that water is within it.

This is a biological range — where the species occurs, not a prediction that you will catch one. To browse the fishing geography FishingHQ holds, start at fishing places.

Why anglers care

The sturgeon an ordinary angler in Europe is most likely to encounter, and the reason the encounter is complicated. In its native Danube basin it is a declining native species and is protected or seasonally protected in most of the bordering jurisdictions, which means an incidental capture there is a release-and-possibly-report event rather than a catch. In stocked commercial and managed fisheries across central and western Europe it is legitimate quarry under the fishery's own terms and is fished for deliberately, usually on bottom methods with soft baits presented on the bed. Those two situations look identical from the bank and are entirely different in law and in consequence, and the difference belongs to the water rather than to the fish. FishingHQ states no rule for either and names the authority. Where sterlet are fished for legitimately, the welfare requirements are the same as for any sturgeon: horizontal support, minimal air exposure, and no vertical lifting.

Handling and returning

Handle as a sturgeon regardless of which situation you believe you are in. Keep the fish in the water, support it horizontally with wet hands, and never lift it by the tail or suspend it vertically — the skeleton is cartilage and will not carry the body's weight. The scutes are sharp, particularly on smaller fish. The mouth is toothless and the fish cannot bite. Sturgeons take a bottom bait confidently and are frequently hooked well back, so long forceps and a willingness to cut the line close are more useful than a determination to recover the hook. If there is any possibility the fish is a protected species — which in the Danube basin there always is — release it immediately and establish the reporting position afterwards rather than holding the fish while you find out.