European dace  (Squalius keadicus)

Classified as Endangered (EN) on the IUCN Red List (1).

A rare freshwater species found only in the Evrotas River in Greece, the European dace is a member of the Cyprinidae family, a diverse group of fish comprising over 2,000 species (1) (3). Most of these fish have scaleless heads and lack teeth, instead possessing a pair of enlarged bones in the throat that grind food against a pad at the base of the skull (3). The European dace has a dark-brownish blue colouration with a dark stripe extending from the eye to the base of the tail (2) (4). Displaying marked sexual dimorphism, the smaller male has comparatively larger pectoral and pelvic fins than the female (2).

The European dace is endemic to the Evrotas River in south-eastern Peloponnese, Greece (1).

The European dace typically inhabits cold, deep, fast flowing areas of the Evrotas, preferring areas with submerged tree roots, aquatic vegetation and a coarse substrate. At early stages in its life and during periods when parts of the Evrotas seasonally dry up, the European dace will also occupy less favourable habitats, including shallower pools with little water flow and a lower oxygen concentration (1) (5).    

A rare and little-studied species, there is, understandably, a lack of information on the biology of the European dace. However, this omnivore is thought to feed throughout the water column, and spawning is thought to take place in mid-spring, from the second-half of April through the beginning of May (2) (4) (5). Juvenile fish typically mature in the second year of life, although some males may mature in the first (2).

Restricted to just a single river, the European dace is primarily threatened by the loss of its habitat. Although the Evrotas River naturally dries up during periods of drought, water extraction for agriculture has exacerbated this, resulting in fish being stranded in stagnant pools of water with low oxygen concentration and high temperatures (1) (6). This was most severe in 2007 when a prolonged drought resulted in around 80 percent of the main river course drying up (6). As the European dace inhabits fast flowing, cold waters, mass fish mortality has been observed in areas where its habitat has been degraded in such a way (5). Fish communities within the Evrotas River have also suffered from pollution, with lowland parts of the river, often near urban areas, being the most severely effected (1) (6).

The Evrotas River, home to the European dace, is a unique biodiversity hotspot within Greece. Its waters support many endemic species of plants and fish and, consequently, protecting this fragile environment is a key conservation priority (6). The importance of this river and a plan for its conservation, is outlined in the EU Water Framework Directive. This requires habitat monitoring and management programmes to be implemented whilst tackling the threats to the river (6) (7). Furthermore, establishing protected areas and developing sustainable water management plans will be crucial in preserving the European dace for the future (1) (2).

For additional information on the European dace, see:

• Economou, A.N., Barbieri, R. and Stoumboudi, M.T. (2005) Threatened Fishes of the World: Leuciscus keadicus (Stephanidis 1971) (Cyprinidae). Environmental Biology of Fishes, 73: 252.