The white muscle PFK activity from sea bass (Dicentrarchus labrax L.) shows a biphasic kinetic with respect to the two sunstrates, fructose-6-phosphate and Mg-ATP^2- complex, because of the existence of two isozymes, PFK-M1 and PFK-M2. PFK activity seems mainly regulated by PFK-M2 isozyme, which shows the highest activity and regulation. This regulation comes principally from F6P substrate and fructose-1-6-bisphosphate. PFK activity is not inhibited by the Mg-ATP^2- substrate. Magnesium produces activation on it, though performing activation on PFK-M2 and inhibition on PFK-M1. PEP acts as a light activator of PFK-M2 but it does not affect PFK-M1 activity. Form PFK kinetic-regulatory characteristics and physiological concentrations of substrates and metabolites it is possible that the glycolysis will be active in sea bass white muscle.