ABSTRACT This research aim to determine the optimal dose of additional probiotic EM4 in feed to the growth performance and survival rate of Catfish (Ompok hypopthalmus) by using biofloc system on peat swamp water. This research was conducted on 40 days from June,13 to August 2, 2019 at Technical Service Unit (UPT) of Hatchery, Faculty of Fisheries and Marine, University of Riau. This rese…