Danube bleak Danube bleak The Danube bleak or Caspian shemaya ("Alburnus chalcoides") is a species of freshwater fish in the family Cyprinidae. It is found in Iran, Austria, Bosnia and Herzegovina, Bulgaria, Croatia, France, Germany, Hungary, Italy, Romania, Russia, Serbia, Slovenia, Turkmenistan, and Uzbekistan. The Danube bleak is an elongate slim fish which can reach but a more normal size is 15 to 30 centimetres (6 to 12 in). There are 57 to 70 scales along the lateral line. The abdomen is compressed into a keel and the posterior end of this has no scales. The dorsal fin has eight to nine
Common species because common species shape ecosystems, contribute disproportionately to ecosystem functioning, and can show rapid population declines, conservation should look more closely at how the trade-off between species extinctions and the depletion of populations. Common species Common species and uncommon species are designations used in ecology to describe the population status of a species. Commonness is closely related to abundance. Abundance refers to the frequency with which a species is found in controlled samples; in contrast, species are defined as common or uncommon based on their overall presence in the environment. A species may be locally abundant without being common. However,