The study involved analysis, performed with standard methods, of length and weight growth of 202 perch individuals caught in November 1999 from the Szczecin Lagoon. The verge coefficient was factored in both when determining the age distribution and when analysing length and weight growth by calculating mean values in age groups (when Kr > 0.50, the number of annual rings was increased by 1).
The study involved crucian carp harvested in various seasons of 2000-2002 from the Szczecin Lagoon (177 individuals) and from the Leszczyńskie Lakeland (707 individuals). The fish age was determined from scales. The length growth was back-calculated with the scale radius-corrected Vovk method in which the standard length was set at 12 mm [10]. In addition, 5 mathematical growth models (Ford-Walford, von Bertalanffy, Gompertz, the second order polynomial, and modified power function) were applied. The weight growth was followed by means of the modified von Bertalanffy equation.