Data for Morphological and reproductive analyses

Populations caught in April 2015 were female dominated and characterized with rapid reproduction, since all samples were already mature. The GSI, absolute and relative number of oocytes, and the size of oocytes were significantly different compared to all native as well as non-native areas of occurrence. The smallest mature female reached 26.27 mm, while the mean SL was 41.08 mm between all populations. Samples were characterized with three size groups of oocytes, and the biggest reached oocyte size was 1.46 mm. The absolute as well as relative number of oocytes was higher compared to other studies from native, and non-native areas of occurrence. There was no significant difference in the condition between females and males within each population, thus they were both in good and/or bad condition. Majority of traits were statistically significant, while more than a half can be suggested to have biological importance. Significant differences were related to characters located on the head, fins and associated with the length or height of the body.