Using morphometric, meristic and qualitative characters, we confirmed a specific status of a clade discovered based on molecular data only. The newly described species Phoxinus krkae has a very local distribution in the upper Krka River but is easily morphologically distinguished from geographically neighbouring species with much wider ranges: Phoxinus lumaireul, Phoxinus marsilii and Phoxinus csikii. Phoxinus krkae is well differentiated in statistical analyses and differs from other species of Phoxinus in northern Adriatic Sea drainages and right-bank tributaries of the middle and lower River Danube by a combination of characters, none of them unique: caudal peduncle length 1.9-2.2 times minimum depth of caudal peduncle; upper lip not projecting beyond lower lip; rostral fold absent; total number of scales in lateral series 74-84; lateral line incomplete and interrupted, commonly 17-49 (< 60% of total number of scales in lateral series) with no or few canal segments on posterior body and caudalpeduncle; scales on belly extending forward to over middle of distance between pelvic-fin base and pectoral-fin origin; patches of breast scales commonly connected by scattered scales or forming 1-3 regular rows of scales; total vertebrae commonly 38-39 (22 + 17, 22 + 16 or 21 + 17). The study reveals unrecognised morphological diversity within the group and provides the groundwork for future taxonomic study in Phoxinus in the Adriatic region and the Danube Basin.

Squalius microlepis was examined from recent and historical collections within the known range of the species with special emphasis on intraspecific variability and variations, and compared to its closest relative species S. tenellus (in total, 193 specimens; 33 absolute and 52 proportional measurements and ratios, and 12 counts including vertebrae). Squalius tenellus was perfectly differentiated in all statistical analyses and can be diagnosed by 76–95 (vs. 64–80) scales in lateral series, 68–83 (vs. 58–77) lateral-line scales, (17)18–20 (vs. 13–16(17)) scales above lateral line, and (7)8–10 (vs. 4–7) scales below lateral line. Squalius microlepis was morphologically heterogeneous, with two phenotypes readily distinguishable (phenotype 1 corresponding to S. microlepis s. str. as defined by its lectotype) by a combination of many characters; those contributing most to the discrimination were number of gill rakers, length of lower jaw (% interorbital width), and head length (% SL). Only phenotype 1 was found in the Ričina-Prološko Blato-Vrljika karst system; most of the specimens from the lower Matica and the Tihaljina-Trebižat karst system were identified as phenotype 2; the sample from karstic poljes near Vrgorac contained both phenotype 1 and 2, and individuals of intermediate morphology. As very limited molecular data exist on the two phenotypes of S. microlepis, we refrain from any taxonomic conclusions until new molecular approaches (and new markers) are used. We also report on a dramatic reduction of the area of distribution and abundance of S. microlepis in recent years.

Alburnus sava, new species, is described from the Kolpa River. The Kolpa is a tributary of the Sava, a major tributary of the Danube River, in the Black Sea basin. Alburnus sava is distinguished from its congeners in the Danube drainage, A. mento and A. sarmaticus, by having 23−27, usually 24−26, gill rakers; the ventral keel usually completely covered by scales (scaleless part maximum 15% of the keel length); 15−16, mode 15, branched pectoral-fin rays; the length of the gill raker at the junction of the arch limbs 65−70% of the length of the opposite outer gill filament; and a relatively long lower jaw (37−40% HL or 112−130% interorbital width). Alburnus sava is a large-sized potamadromous shemaya known to occur in the entire Sava drainage. The taxonomic status of A. mento and A. sarmaticus is confirmed. Alburnus danubicus is discussed and as there are no new arguments, it is kept as a valid species. New details on the distribution of shemayas in the Danube drainage are presented.

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The Sea of Azov, bounded by Ukraine and Russia, is a unique brackish waterbody from many points of view despite its small size. Low water salinity, shallow waters, high summer temperatures, large riverine inputs of organic matter and minerals, and other factors lead to its very high biological productivity. The article reviews specific features of the Sea of Azov fish fauna and fisheries providing some historical and modern statistical data. An updated check-list of native and non-indigenous fish taxa permanently or occasionally inhabiting the Sea of Azov is included.