The classification of European rivers comes from the fish fauna found in them. Changes in taxonomic composition relate to physical and chemical changes that occur longitudinally.
Morské oko is a lake in the Vihorlat Mountains in eastern Slovakia. It is the largest non karst lake and the third biggest natural lake in Slovakia. It is at an altitude of 618 m, covers 0.13 km² with a maximum depth of 25.1 m. It is drained by the river Okna.
Barbatula is a genus of fish in the family Nemacheilidae native to Europe and Asia. They are found in streams, rivers and lakes, and the genus also includes Europe's only cavefish, which only was discovered in the Danube–Aachtopf system in Germany in 2015.
The stone loach is a European species of fresh water ray-finned fish in the family Nemacheilidae. It is one of nineteen species in the genus Barbatula. Stone loaches live amongst the gravel and stones of fast flowing water where they can search for food. The most distinctive feature of this small fish is the presence of barbels around the bottom jaw, which they use to detect their invertebrate prey. The body is a mixture of brown, green and yellow.
Oxynoemacheilus theophilii is a species of stone loach native to Turkey and the island of Lesbos in Greece. This species occurs in streams and reaches a length of 6.6 centimetres (2.6 in) SL. It is found in the Büyük Menderes River and other streams in western Anatolia, Turkey, and the Evergetoulas Stream on the island of Lesbos, Greece. It can be found in the upper reaches of streams with clear, cold, flowing water where it hides among the stones of the stream bed. The stomach contents of a single female were found to consist of aquatic insect larvae. Water abstraction and the increased droughts caused by climate change are the main threats.
Barbatula dgebuadzei is a species of ray-finned fish in the genus Barbatula, which belongs to the family Nemacheilidae, the stone loaches. This loach is endemic to Mongolia where it occurs in the Baidrag-Gol River drainage, Gobi Lakes Valley.
Oxynoemacheilus argyrogramma, the two-spot loach is a species of ray-finned fish in the genus Oxynoemacheilus. This species is found in the drainage of the Queiq River in Syria and Turkey, and the upper Euphrates drainage in Turkey and possibly in this drainage in Syria and Iraq. It has almost been extirpated from the Queiq as this river has virtually dried out but it remains abundant in the Euphrates. This species can be found in a wide range of habitats as long as there is a moderately fast current from small upland streams to banks of large rivers. It can also occur in stagnant water bodies such as reservoirs. It is threatened by water abstraction, lowering rainfall due to climate change and the construction of dams. The economic development of the area where this species occurs exacerbates these threats. Freyhof and Özuluǧ published a paper in 2017 that argued that Oxynoemacheilus euphraticus was a valid species and not a synonym of O. argyrogramma.
Oxynoemacheilus germencicus, the Carian loach, is a species of Cypriniformes fish in the genus Oxynoemacheilus. It is known only from the Büyük Menderes River and lower Gediz River in western Anatolia, it probably also occurred in the Kücük Menderes, a river which sits between the Büyük Menderes and Gediz, and has been extirpated from that river by pollution and abstraction. It remains widespread and locally abundant in the other two rivers but the populations have declined and the species is threatened by climate change reducing rainfall in the area and human activities such as damming and water abstraction as well as pollution>
Barbatula nuda is a species of ray-finned fish in the genus Barbatula, which belongs to the family Nemacheilidae, the stone loaches. This loach is found in the Liao and Taizi River drainages in northern China and in northern North Korea.
Barbatula quignardi, the Languedoc stone loach or Les stone loach,, is a species of ray-finned fish in the genus Barbatula, which belongs to the family Nemacheilidae, the stone loaches. This loach is found in the drainage of Ebro, Bidasoa and Nervión in Spain and Lez, Tech, Adour and Garonne drainages in France
Barbatula toni is a species of ray-finned fish in the genus Barbatula.
Barbatula zetensis, also known as the Zeta stone loach, is a species of Cypriniformes fish in the genus Barbatula it is found in the drainage of the River Morača in the Lake Skadar basin in Montenegro. It is common in streams and rivers with stone bottom.
Barbatula potaninorum is a species of ray-finned fish in the genus Barbatula, which belongs to the family Nemacheilidae, the stone loaches. This loach is found in northern China and Inner Mongolia.
Barbatula sawadai is a species of stone loach in the genus Barbatula. It is native to the Selenga River basin in Mongolia and Russia
Cystidicoloides tenuissima is a species of nematodes in the order Spirurida and family Cystidicolidae. It is a parasite of salmonid fish in the northern hemisphere and has mayflies as the alternate host.
Holostephanus cobitidis is a species of parasitic trematode in the family Cyathocotylidae.
Barbatula cobdonensis is a species of freshwater ray-finned fish belongig to the family Nemacheilidae, the stone loaches. This loach is found in the lakes Khintiktig-Khol and Ak-Khol and in the Mogen-Buren River all within the drainage basin of the Kobdo River in northwestern Mongolia and the Tuva Republic in Russia. This taxon is placed with some uncertainty within the genus Barbatula as a species inquirenda, or it may be a junior synonym of B. compressirostris.
