The aim of this work is to evaluate how changes in a set of different key operational factors (e.g., the unit sales price, the fingerling unit cost, the feed unit cost, and so on) would impact on the economic performance of a typical grow-out farm producing European sea bass in the Mediterranean under different scenarios of production related to the farm size (production volume) and production strategy (size of the produced fish). A what-if analysis using a deterministic static model to simulate the annual income statement of a typical grow-out farm was carried out. Data was obtained from ten European facilities located in the Mediterranean Sea. Our findings show the importance of the farm’s scale and the production of larger fish to obtain better economic results. Another important conclusion is that increase in fish growth and survival rates, innovating in feed and improving the breeding and health conditions, could compensate the reductions in the sea bass sales prices more efficiently than using other alternatives.