Similar to other invasive species, stone moroko is extending its global distribution.
The present study aimed to assess the reproductive potential of stone moroko fish in a new habitat in
Poland based on analysing the sexual cycle and fecundity. Fish morphometric data, age, and gonadal
structures were analysed. Fish age ranged from 0+ to 5+ years. Most females and males (93% and
60%, respectively) had reached sexual maturity in the first year of their life, with the smallest length
of 25 mm and 28 mm, respectively. The mean, standard length of the body was 50 mm. The spawning
season was spread over four months from late-April to mid-August. Females laid eggs in portions,
and the absolute and relative fecundity was 1372 and 1691, respectively. Stone moroko males were
ready to spawn for a longer time period than females. The present study shows greater reproductive
potential of stone moroko population in the central Europe than the native population, suggesting its
successful colonisation in the new habitat.