Growth patterns of the golden loach, Sabanejewia balcanica were examined in the Rijeka River in Central Croatia on a total of 77 specimens collected in a single sampling session in June 2006. No significant difference was found in total body length between males and females. Age was determined from otoliths. Both males and females live 4 years, though due to the sampling period, no 0+ age fish were found in this study. The length-weight relationship was calculated as W=2x10-6TL3.3229 for males and W=3x10-6TL3.2811 for females, indicating positively allometric growth. According to the growth factor k, growth of males was three times faster than that of females.
Taxonomic analyses of four Sabanejewia balcanica populations from Croatia included morphological (morphometric, meristic, phenotypical) and mitochondrial DNA analyses. Comparative analyses of 24 morphometric characters revealed some differences between populations. The specimens from the Drava River are significantly larger than specimens from other populations, whereas the individuals from the Voćinska River represent the smallest European S. balcanica specimens. Due to similarities in morphometric ratios, in the Tree Diagram of Euclidean distances, the Drava and Petrinjčica Rivers populations formed a separate cluster, while the populations from the Rijeka and Voćinska Rivers formed a second cluster. These morphometrical differences are also corroborated by t-test results. Differences among fishes from different populations also exist in external morphology characters, such as spots on the caudal peduncle and the position of the suborbital spine. Mitochondrial DNA analyses enabled us to infer the phylogenetic placement of four Croatian populations within the genus Sabanejewia. All Croatian samples clustered within the two sublineages of the Danubian-Balkanian complex. Samples from the Voćinska River, as well as one sample from the Drava River were included in the “S. balcanica” (VI) sublineage. The remaining samples, including the two remaining haplotypes from the Drava River, were comprised within “S.montana-S.bulgarica-S.balcanica” (III) sublineage.
In Slovakia, Cobitis elongatoides (Bacescu et Mayer, 1969), Sabanejewia balcanica (Karaman, 1922), and Misgurnus fossilis (Linnaeus, 1758) are protected by national legislative, and localities of European importance have been delimited for these species within the Natura 2000 system. In Slovakia, the three species only occur in the Black Sea river system (the Danube and Tisza R. basin). Of them, C. elongatoides is the most widely distributed and most numerous both in its pure form and its hybrid, diploid-polyploid complexes (C. elongatoides x C. tanaitica). It occurs in proper streams and in natural as well as in artificial aquatic habitats, above all, in lowland regions. Comparing data on this species from 1955–1965, no major changes have been found. S. balcanica occurs chiefly in the middle reaches of rivers, first of all, in the Bodrog drainage area (the Laborec, Ondava, Topľa R.) in eastern Slovakia. In the western part of Slovakia (the Danube river system) the occurrence of this species is distinctly less frequent and insular. The distribution of the species has been markedly affected by water pollution, construction of dams and reservoirs, and river bed modifications. The occurrence of M. fossilis is almost exclusively limited to the lowland regions of eastern Slovakia and the Danube Lowland. In those regions, the amelioration measures taken during the second part of the 20th century caused the original natural wetlands to vanish – together with the occurrence of this species. However, M. fossilis found a secondary suitable environment in man-made hydro-amelioration channels, earth pits, and fishponds.