A field study was conducted to assess the effect of mono-and polyculture systems of Florida red tilapia (Oreochromis sp. and thinlip grey mullet (Chelon ramada) in concrete tanks. Growth performance, feed efficiency, body chemical composition, and health status of the experimental fish were evaluated after 42 days rearing period. Five experimental treatments were carried out as follow: T1= 100% red tilapia; T2= 75% red tilapia and 25% mullet; T3= 50% red tilapia and 50% mullet; T4= 25% red tilapia and 75% mullet; and T5= 100% mullet. Fish of T1 showed the highest values of growth performance, feed utilization, and productivity, while T5 showed the lowest levels. Mullet did not show any significant positive effect when co-cultured with red tilapia in a concrete tank. Rearing red tilapia under the monoculture system is much better than the polyculture system with mullet as the latter species have one-third growth performance, feed utilization, and productivity that of red tilapia. Contrary to what was expected, the co-culture of mullet did not significantly improve the parameters of water quality, fish performance, flesh quality, blood analyses, and heavy metals content in red tilapia.