Comparative investigation of some growth characteristics of the bitterling (Rhodeus amarus Bloch, 1782) in aquatic ecosystems of Anzali lagoon and Siyahrood River

A comparative study of species in different habitats at the population level is very important because such studies provide significant information about the diversity of species. In this study the growth characteristics of bitterling was investigated in two different aquatic waters in Anzali lagoon and Siyahrood River. The sampling was monthly done by plankton-collector from February to June 2013 and a total of 538 specimens were collected. To determine age opercula and scales were utilized .There were 7 age groups of 2 till 8 in Anzali lagoon and 8 age groups of 1 till 8 in Siahrood River. The result showed that the largest length and weight were 75.44 mm and 6.674 g for males in Siyahrood River. A significant weight-length relationship was observed for the populations in different areas (P