D. Klisarova1,2, D. Gerdzhikov1* 1Institute of Fish Resources, Agricultural Academy, Varna, 9000, POBox 72, Primorski 4 2Medical University – Pleven, 5800, Saint Kliment Ohridski Street, 1 (Manuscript received 18 July 2022; accepted for publication 15 August 2022) Abstract. Mari