Biological parameters such as growth and mortality are vital for stock assessment and management. Using length composition data of BET in the Indian Ocean in 2011 (combination of longline and purse seine fisheries), the growth and mortality parameters were estimated by using ELEFAN technique with FiSATII software. The von Bertalanffy growth parameters were estimated at L_∞=270.9 cm (fork length), k=0.08, and t₀=-1.194 a. The total mortality rate estimated by length converted catch curve method was 0.61. The fishing mortality rate and the exploitation rate was 0.21and 0.34, respectively. The analysis of yield-per-recruit suggested that the bigeye tuna stock was not under high fishing pressure in the Indian Ocean. This study provides the estimates of growth and mortality rate for bigeye tuna, which can be used as biological parameters for further evaluations of stock status in the Indian Ocean.