Fish play an important role in Danube rivers. Fish are more than just a valuable source of nutrition for the human population; their healthy numbers serve as an important indicator of the biological quality of the river.

Beluga Sturgeon (Huso huso)

The Beluga sturgeon is the largest freshwater fish in the Danube system and can live up to 100 years. Beluga sturgeons are capable of moving freely between freshwater and estuaries. Adult Beluga sturgeons swim at middle depths and, in the Black Sea, prey on species such as flounder and other flatfish, gobies and Black Sea anchovy.

The Beluga sturgeon is famous for the caviar produced from its roe. World demand for caviar far exceeds the available supply, forcing legal fishers to catch increasingly younger and smaller fish, fuelling a growing black market.

Danube Streber (Zingel streber)

The Danube streber is yellow-brown in colour and has several dark bands crosswise along its body. The average length is approximately 15cm, but it can grow to over 18cm long.
The Danube streber is found in fast-flowing river stretches. It becomes active after sundown when it searches for food. A remarkable characteristic of the Danube streber is its ability to hold itself on the riverbed, against even the strongest currents. It feeds almost exclusively on organisms that are driven near it by the water.

Danube Salmon (Hucho hucho)

This large freshwater fish has an elongated body, a large head and mouth and strong teeth. The back of the Danube salmon is grey-brown to red-brown in colour and patterned with numerous dark spots; the sides are reddish grey with a copper-coloured gloss and the belly is silvery-white.
The Danube salmon is one of the most endangered fish species in Europe. It prefers cool, oxygen-rich water and is an excellent indicator of good water quality.

Sterlet (Acipenser ruthenus)

The sterlet has a narrow, pointed snout with four long, fringed barbels. It has a tail like that of a shark, with the backbone continuing into the top lobe, which is longer than the bottom lobe. Sterlets grow to a maximum length of 70cm.
The sterlet inhabits main rivers and their tributaries, living in brackish freshwater at depths of around 1m. It uses its sensitive barbels to locate food, preferring insect larvae, worms and snails.

European Catfish (Silurus glanis)

The European catfish is distinguished from other catfish by its broad flat head and large size. It is the world’s largest catfish, growing between 1-2m in length and over 100kg in weight; it can live up to 80 years.
The European catfish prefers large lakes and slow moving deep rivers. They are mainly nocturnal and hide in dark places under banks and overhanging roots, where they feed on fish, frogs, birds and small mammals.

Pike (Esox lucius)

The pike can be identified by its single dorsal fin and light coloured spots along its body, which varies in colour from dark shades of green to brown. The belly is white to cream coloured. Pike can grow up to 100cm long.
Pike are found in almost every type of freshwater, from cold deep lakes, to warm shallow ponds, to muddy rivers. Pike are aggressive fish and able to attack quickly. They are considered ‘sprint predators’, hiding under cover, ready to strike. They can sprint at speeds of up to 4m/s or 14km/hr.

Pike-Perch (Sander lucioperca)

The pike-perch is a member of the perch family. It has a long, slender body and a small, narrow head. The pike-perch has two dorsal fins, the first spiny, the second soft. Usually greenish-grey or brown, black dappling occurs in stripes which fade with maturity. Its average length is between 40-50cm but some may grow up to 120cm long.
The eyes of the pike-perch are much larger than that of the pike. They have a reflective material behind the eye that helps them make the most of low light conditions: they are often nocturnal feeders. Pike-perch inhabit the deep, calm waters of lakes, reservoirs, canals and rivers.

Burbot (Lota lota)

The burbot resembles an eel with its long body tapering to a round tail. It has two dorsal fins: one short and followed by a much longer second fin that joins to a rounded caudal fin. Colouration varies from yellow-brown to dark olive green with black mottling. The male burbot reaches an average length of 50cm; the female approximately 150cm and a weight of 4kg. It prefers freshwater and is found in deep temperate lake bottoms and slow-moving cold rivers.

Danube Roach (Rutilus pigus)

A member of the carp family, the Danube roach has a round, blunt snout. They are silvery-grey, with a shiny mother-of-pearl body, dark back and orange-red fins. Their average length is 40cm. It lives in slow-moving rivers and the deeper parts of lakes.

Bream (Abramis brama)

The bream has a thin, flattened body with a high back. It is silvery-grey, though older bream can be lightly bronze coloured. It has long pectoral fins, distinguishing it from the white bream (see below) with which it is sometimes confused. The bream grows to between 30-50cm long; weighs 2-4kg and can live as long as 20 years. They live in the lower reaches of slow-moving rivers and in nutrient-rich lakes and ponds. Bream are bottom-feeders, living mainly on insect larvae.

Knife (Pelecus Cultratus)

The knife is, not surprisingly, shaped like a cutting blade: thin with a straight back and a curved, sharp belly. It grows to 60cm in length and 2kg in weight and lives up to 11 years. It is found in the lower reaches of rivers and brackish waters of the Black Sea.

Blue Bream (Abramis ballerus)

The blue bream belongs to the carp family and has bluish-black and silver flanks. Characteristics are its feather-like tail and upturned mouth. Average length is between 20-3cm. It is normally found in the lower reaches of rivers and lowland lakes and in the brackish water of the Black Sea.

Nase (Chondrostoma nasus)

The nase can grow up to 50cm in length and 2kg in weight and live up to 15 years. It lives in the upper reaches of the Rhine and Danube River Basins and is found in fairly shallow fast-flowing water, often beside the swirls created near bridges or piles of rocks. Nase feed on the algal growth found on stones, which is scraped away with the use of its sharp mouth.

Schraetser (Gymnocephalus schraetser)

The schraetser is a member of the perch family. Characteristics are thick lips and a yellow-green colour with black stripes running the length of the body. Average length is 15cm. The schraetser inhabits the deeper parts of the Danube River.

Asp (Aspius aspius)

The asp has a long, thin body with a long, sharp head and small scales. Its overall colour is silver with a blackish-olive or greenish-grey back. It grows to 100cm long and 9kg and lives to 11 years. Inhabiting the lower reaches of rivers and estuaries, it prefers to stay near bridge pillars, under weirs, in deep currents, overgrown sections and in quiet bays of river bends. The asp is a solitary predator of other fish, such as gobies and silversides, but may also feed on frogs and small birds.

Zingel (Zingel zingel)

The zingel is a member of the perch family. It has a mottled brownish-reddish colouring and grows to 50cm long. Zingel are found in shallow waters of the Danube, Prut, and Dniestr Rivers. They are mainly nocturnal and feed on bottom-dwelling animals, fish eggs and larvae.

Danube Bream (Abramis sapa)

The Danube bream is silvery-grey with reddish fins and grows up to 35cm long. It is found in the fast-flowing rivers of the Danube Basin.

White Bream (Abramis bjoerkna)

The white bream is silvery-grey and grows up to 36cm in length and 1kg in weight. It prefers the stagnant waters of lakes and reservoirs and rivers and canals with calm waters. It feeds on small bottom-dwelling animals, insect larvae and plants.

Danube Ruffe (Gymnocephalus baloni)

The Danube ruffe is a small fish, growing to a maximum size of 12cm. Though small, the Danube ruffe is a resilient fish, doubling its population in less than 15 months.

Barbel (Barbus barbus)

The barbel is a large, powerful member of the carp family. Greenish-brown in colour, it takes its name from the several barbels which surround its mouth. It is a long-living fish and can grow to 120cm and 12kg. It lives in the deeper, fast-flowing upper reaches of rivers with a stony or gravel bed. The streamlined barbel can hug the riverbed while feeding on passing small crustaceans, insect larvae and molluscs.

Email danubeday [at] aqa [dot] at to receive a free copy of a poster showing the Danube fish or download it below.

The ICPDR would like to thank the following individuals and institutions for providing scientific support in preparing the fish poster: Zdenek Adamek (Department of Fish Ecology, Academy of Sciences of the Czech Republic); Erik Bohl (Agency for Environment and Water Management, Bavaria, Germany); Grigore Davideanu (Aquaterra Ecological Society, Romania); Institute of Hydrobiology and Aquatic Ecosystem Management (University of Natural Resources and Applied Life Sciences, Vienna); Federal Agency for Water Management of Austria.

Poster_Danube fish.pdf 1.33 MB