European mudminnow (Umbra krameri)
|Size||Maximum length: 17 cm (2)|
Average weight: 5 - 8 g (3)
Maximum weight: 27 g (3)
Classified as Vulnerable (VU) on the IUCN Red List (1).
The European mudminnow is a small, freshwater fish, with a large head, rounded snout, dark brown body and a whitish belly. The sides of the body sometimes have a bluish tint, while a light stripe runs along the body and a scattering of brown spots decorate the back and sides (2) (3). It has a long dorsal fin and a long, rounded caudal fin (4). The female European mudminnow is larger than the male (2).
The only Umbra species found in Europe (2), the European mudminnow is also sometimes called the ‘dog-fish’, due to the way it move its pectoral fins alternately when swimming, like the feet of a running dog (4).
The European mudminnow occurs in the lowlands of the Danube River drainage, from Vienna, Austria to the Black Sea, and in the lower reaches of the Dniester drainage (Ukraine and Moldova) (1).
This freshwater fish inhabits slow flowing and stagnant waters (2), such as ditches, ponds, oxbow lakes (5), marshland and swamp regions. It favours areas of dense vegetation where water temperatures range from 5 to 24 degrees Celsius (2).
The European mudminnow lives for up to five years (1), becoming sexually mature within the first year of life (1) (2). Spawning, where the female releases yellowish-orange, sticky eggs into the water, takes place in March and April. The female selects a suitable nest site, either a spot over roots or watermoss, or a nest made of plant material in a depression at the bottom, and releases six to eight eggs at a time, which are then fertilised by one or more males. This process is repeated multiple times, with the female usually depositing a total of up to 200 eggs. After spawning, the female aggressively guards the eggs until hatching (2) (3) (6).
The newly hatched larvae initially rest at the bottom or attached to various objects, and remain largely motionless except for their waving pectoral fins (3). About a week after the eggs have hatched, the young European mudminnows begin moving around and feeding on live food (2), such as tiny crustaceans. At the end of the first summer, they start eating larger food items (3). The European mudminnow is known to feed primarily on animals found at the water’s bottom, such as small shrimps and snails, although beetles and other insects are also sometimes taken from mid-water or the surface (3).
The mudminnow can survive in extremely low oxygen conditions due to its ability to use its swimbladder for air breathing (2) (3), and can reportedly survive for more than two days in the winter without water (3).
The European mudminnow population has declined considerably over recent years (1). This is largely due to modification of its natural habitat, as river regulation for water transport has reduced the number of oxbow lakes and other suitable areas of water, and wetlands have been drained for agriculture (1). In addition, the loss of shallow ditches, introduced fish species, and chemical pollution continue to threaten the European mudminnow (2). Its reproductive strategy (the relatively small numbers of eggs produced, and energy-draining parental care) renders it quite sensitive to environmental change, causing it to suffer more from various human disturbances than most other freshwater fish (2) (5) (7).
The European mudminnow is protected by law in some countries (2), such as in Hungary where local action plans have been developed, and it is also included in the national Red Lists of Slovenia, Croatia, Moldova and Austria (1), which should help focus attention on its conservation needs. In Bratislava, Slovakia, attempts have been made to breed the European mudminnow in both laboratory and semi-natural conditions (5), and in the Danube, dams are being opened to reconnect the river’s backwaters, increasing habitat availability for the fish (8). In Bosnia and Herzegovina a population of the European mudminnow has been discovered in Gromizelj, a Special Nature Reserve, and in order to conserve this newly discovered population, protection levels of this area are being increased (9).
As the protection of the European mudminnow’s habitat is central to its survival, it has been recommended that measures are implemented to prevent the destruction or replacement of small irrigation ditches with large, deep canals (2).
To find out about environmental issues affecting the Danube river basin see:
International Commission for the Protection of the Danube River:
Danube River Network of Protected Areas:
Authenticated (23/08/10) by Dr Josef Wanzenböck, Institute for Limnology, Austrian Academy of Sciences.
- Caudal fin: the tail fin of a fish.
- Crustaceans: a diverse group of animals with jointed limbs and a hard external skeleton. All crustaceans have two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
- Dorsal fin: the unpaired fin found on the back of the body of fish.
- Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Oxbow lake: a crescent-shaped lake that is formed when a meander (bend) of a river is cut off from the main channel.
- Pectoral fins: the fins that are found on each side of the body, just behind the gills. They are generally used for balancing and braking.
- Spawning: the depositing of eggs in water.
- Ventral fins: the pair of fins found on the underside of the body.
IUCN Red List (May, 2010)
- Povz, M. (1995) Threatened fishes of the world: Umbra krameri Walbaum, 1792 (Umbridae). Environmental Biology of Fishes, 43(3): 232.
- Wanzenbock, J. (1995) Current knowledge on the European mudminnow, Umbra krameri WALBAUM 1792. Annalen des Naturhistorischen Museums in Wien, 97B: 439-449.
- Bateman, G.C. (1904) Freshwater Aquaria – their Construction, Arrangement and Management. Second Edition. L. Upcott Gill, London.
- Kovac, V. (1997) Experience with captive breeding of the European mudminnow, Umbra krameri Walbaum, and why it may be in danger of extinction. Aquarium Sciences and Conservation, 1: 45–51.
- Bohlen, J. (1995) Laboratory studies on the reproduction of the European mudminnow, Umbra krameri Walbaum, 1792. Annalen des Naturhistorischen Museums in Wien, 97B: 502-507.
- Sekulic, N., Budakov, L. and Brankovic, D. (1998) Distribution of the European mudminnow Umbra krameri (Umbridae) in Serbia. Italian Journal of Zoology, 65(1): 381-382.
- Akcakaya, H.R., Mills, G. and Doncaster, C.P. (2006) The role of metapopulations on conservation. In: Macdonald, D.W. and Service, K. (Eds.) Key Topics in Conservation Biology. Blackwell Publishing, Oxford.
- IUCN Programme Office for South-Eastern Europe (2009) New habitat of Umbra krameri. IUCN South-Eastern European e-bulletin, 20: 12.