White-leg shrimp Litopenaeus vannamei juveniles (0.95±0.03g initial weight) and red seaweed Gracilaria tenuistipitata were co-cultured in 250-L tanks for 75 days. Five feeding treatments were performed, with the control group (monoculture) being fed a commercial shrimp feed at 100% feed ration (8% of biomass per day), while shrimp in the four other groups were co-cultured with red seaweed and received commercial feed at 85%, 70%, 55% and 40% of the feeding ration of the control. The results showed that the concentrations of the TAN, NO₂^-, NO₃^-, TN, PO₄^3-,TP, and COD in the co-culture tanks were significantly lower than in the monoculture. Survival, growth rates and production of the shrimp fed at 85%, 70% and 55% feed ration of the control were superior to those in the control group (pL. vannamei with G. tenuistipitata helped improve water quality, performances, feed efficiency and of shrimp. Based on the survival, production and feed  conversion ratio and feed cost data, it can be stated that shrimp co-cultured with red seaweed applied 55% feeding rate could be the optimal feeding level.