Fluctuating asymmetry (FA), the random deviation from perfect bilateral symmetry, is the basis of an acknowledged method to analyse developmental stability in animals and plants. This study investigates the fluctuating asymmetry in perch(Perca fluviatilisL.) from one natural lake (Trasimeno) and two regulated lakes (Corbara, Piediluco) of central Italy. Seven morphometric (pectoral and ventral fins length, pre‐pectoral fin distance, pre‐ventral fin distance, pectoral‐ventral fins distance, postorbital distance, head length) and six meristic (lateral line scales, pectoral and ventral fins rays, mandibular pores, upper and lower gill rakers) bilateral characters were selected to detect fluctuating asymmetry. Total and standard length, weight, sex and age were employed to investigate growth of perch. On the basis of FA levels a comparison of the three lakes was then made. Statistical analysis shows a relationship between fluctuating asymmetry levels and growth, and the possibility to order the lakes according to FA levels. Therefore, FA can be considered a tool to detect stress occurring during development.