TY JOUR TI OPTIMIZATION OF STAGES OF PRE-SPAWNING AND SPAWNING PERIODS OF TILAPIA IN COMMERCIAL GROWING KW aquaculture KW tilapia KW optimization KW spawning KW feeding KW producers KW pH JO Vestnik of Astrakhan State Technical University. Series: Fishing industry AU Vasil'eva, E.G. AU Melnik, I.V. PY 2021 IS PB Astrakhan State Technical University