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Growth and survival rates (specific growth rate -SGR; survival rate -S) of Barbus barbus L. were recorded in captivity during three years from the larval period (final body weight -W = 0.2 ± 0.03 g; SGR = 13.6 ± 1.1%/day and cumulative survival -S = 76.0 ± 2.5%) to the first reproductive season (W = 62.55 ± 13.5 g; SGR = 0.89 ± 0.05%/day; S = 59.3 ± 1.5%). Final body size and SGR were compared between both sexes. Females reached the significantly higher growth rate (SGR = 0.84 ± 0.01%/day) compared to males (SGR = 0.77 ± 0.01%/day). Early puberty was observed in 17 and 32 months old males and females, respectively. Multi-stripping activity was found out in both sexes during the first reproductive season. In total, 20%, 25.8%, 30.3%, 14.6% and 9% of females were stripped once, twice and three, four and five times, respectively. But all males produced sperm during the entire reproductive season. The highest and the lowest egg production was recorded in the middle (April) and at the beginning (March) of the reproductive season (2155 ± 925 vs. 1279 ± 298 eggs per stripping). The highest and the lowest sperm production was observed at the beginning (March) and at the end (May) of the reproductive season (7.9 ± 0.08 × 10 9 vs. 1.9 ± 0.06 × 10 9 per stripping).

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Four broodstocks of European huchen (Hucho hucho) from: Poland, Germany, Slovakia, and Ukraine were investigated using ten microsatellite DNA loci. Microsatellite DNA analysis was successfully applied for the first time in the Polish broodstock of this fish species. The genetic variation and genetic distance between these broodstocks were evaluated. In addition, we examined the potential effects of a genetic bottleneck on the genetic variation of the broodstocks. The European huchen broodstocks exhibited moderate genetic diversity (PIC = 0.405–0.496 and I = 0.831–1.047) with the exception of German broodstock which presented higher genetic diversity (PIC = 0.590 and I = 1.254). Observed (Ho) and expected (He) heterozygosity across the investigated loci in all broodstocks ranged from 0.434 to 0.686 and from 0.452 to 0.650, respectively. Overall, the studied broodstocks were in Hardy-Weinberg equilibrium (HWE); however, from 8 to 42 % of the loci deviated from HWE in each stock. The Garza-Williamson index (M = 0.146–0.279) and values of the heterozygosity excess revealed a reduction of genetic variation in all studied broodstocks because of the founder or bottleneck effect. The analysis of genetic differentiation (Fst) and Nei’s genetic distance between pairs of broodstocks revealed that Polish and Ukrainian broodstocks of European huchen were characterized by the closest genetic distance. In contrast, the highest genetic divergence parameters (Fst and Nei’s distance) were observed among German, Slovak, and Ukrainian broodstocks.

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