Because of a decrease in production and increase in the cost of fishmeal, there is increased interest in the use of plant-based feed in aquaculture. However, one of the major problems associated with the use of plant protein in fish feed is the presence of anti-nutritional factors, such as phytate, which is the primary storage form of phosphorus. Phytate is essentially unavailable to monogastric or agastric aquatic animals as they lack intestinal phytase that promote phytate hydrolysis during digestion. To address this issue, diets for monogastric or stomachless animals are often supplemented with monocalcium phosphate (MCP) to meet their phosphorus requirements. However, MCP is derived from fossils so it is a non-renewable resource. Furthermore, the cost of rock phosphorus has increased dramatically over the past several years. Alternatively, exogenous phytase can be added to hydrolyze phytate, and thus improve the use of phytate phosphorus. Thus, the addition of phytase may lower the need for MCP supplementation, thereby lower feed costs. This strategy may also lower the concentration of phosphorus excreted, resulting in lower eutrophication of the surrounding waters. We evaluated whether neutral phytase could partially replace MCP, and thus reduce the dietary inclusion of MCP. The fish (initial body weight: 11.52 ± 0.12 g) were fed one of four diets for 8 weeks: a control diet (designated P1.5) was prepared with 1.5% MCP but without phytase and three other diets (designated as PP1.5, PP1.0, and PP0.5) were supplemented with 1.5%, 1.0%, or 0.5% MCP, respectively, and 200 mg/kg (diet) phytase. Fish fed PP1.0 and PP0.5 had no significant change in weight gain rate(WGR), specific growth rate (SGR), protein efficiency rate (PER), or feed conversion ratio (FCR) compared with the control (>0.05), whereas fish fed PP0 had significantly lower growth performance in the above parameters (>0.05). Phytase addition did not affect body composition. The apparent digestibility coefficients (ADCs) of crude protein and phosphorus increased when fish were fed . Additionally, phosphorus discharge was significantly reduced in fish fed diets in which MCP was replaced by phytase. Our results suggest that the dietary phosphorus requirement for meeting normal growth in black sea bream is0.51%. MCP can partially be replaced by phytase without affecting the growth of black sea bream. A diet containing 200 mg/kg phytase is equivalent to 1% MCP. The partial substitution of MCP by phytase not only reduces inorganic phosphorus addition to the surrounding waters, but also improves use of phosphorus in the feed.