DEVELOPMENT AND GROWTH MODEL DURING THE POST-EMBRYONIC PERIOD OF THE PERCH (PERCA FLUVIATILIS)

The European perch (Perca fluviatilis) has gained increasing attention in freshwater aquaculture due to its high market value and adaptability to controlled rearing systems. However, the post-embryonic period remains a critical developmental stage, characterized by high sensitivity to environmental conditions, pronounced cannibalistic behavior, and specific nutritional requirements. The present study aimed to evaluate growth and development models of Perca fluviatilis during the post-embryonic phase under different culture systems, with a focus on a flow-through system and varying stocking densities. Larvae were reared for 40 days under controlled conditions (temperature: 17.5–21.5 °C; dissolved oxygen near saturation; photoperiod (12L:12D), at four stocking densities (5, 10, 20, and 33 specimens/L). A gradual feeding protocol was applied, transitioning from Artemia salina to formulated feed (46% protein, 25–26% lipids). Growth performance, survival rate, feed conversion ratio (FCR), and specific growth rate (SGR) were evaluated. The results demonstrated that stocking density significantly influenced growth performance and survival. The optimal density was identified at 10 specimens/L, yielding the highest final mean weight (185 mg/specimen) and survival rate (28%). Higher densities resulted in increased SGR values but were associated with reduced survival (as low as 12%) due to intensified cannibalism and competition. FCR values ranged between 1.26 and 1.33, indicating efficient feed utilization across treatments. Water quality parameters remained within optimal limits, ensuring minimal environmental stress. Comparative analysis of culture systems highlighted the advantages of controlled systems (flow-through and recirculating aquaculture systems, RAS) in maintaining stable environmental conditions and improving growth performance, compared to extensive systems, which are more variable and dependent on natural productivity [7]. In conclusion, the post-embryonic development of Perca fluviatilis is strongly influenced by stocking density, temperature, and feeding strategy. The findings provide a scientific basis for optimizing rearing protocols and contribute to the development of efficient and sustainable aquaculture practices for this species.