Determination of Growth Indicators for Cyprinus carpio (Linnaeus, 1758) in Anzali Lagoon, Iran.

<b>Background and Objective:</b> Understanding the biology of fish is crucial for ensuring the sustainable management and conservation of their biodiversity. The objective of this study was to observe the condition factors and length-weight relationships of <i>Cyprinus carpio</i>, which can provide valuable insights into the ecological and nutritional conditions of aquatic animals. <b>Materials and Methods:</b> Condition factor (CF) and length-weight relationship (LWR) for 100 specimens of <i>C. carpio</i> collected from the Anzali Lagoon 2016 (April to August) were studied. To determine the size of each fish, the total length using a caliper with a precision of 0.1 mm and the weight using a balance with an accuracy of 0.1 g was measured. Differences were analyzed using ANOVA with the Tukey's <i>post hoc</i> test. In order to evaluate the differences in sexes each month, a non-parametric Chi-square test was employed. <b>Results:</b> The total length and body weight of <i>C. carpio</i> ranged from 9.1-53.8 cm and 110.3-5565.2 g, respectively. It was observed that there is a strong positive correlation between length and weight (r = 0.96). The results revealed they had a negative allometry growing rate. In the condition factors, there were no significant differences between male and female specimens (p>0.05). The observed sex ratio suggests no significant difference between males and females (p>0.05). <b>Conclusion:</b> The Anzali Lagoon population of <i>C. carpio</i> exhibited allometric growth, as evidenced by a strong correlation between length and weight represented by a high "r" value.