Horse mussels are bivalves found in Kendari Bay and are frequently consumed by the people in the surrounding coastal communities. The population dynamic of this mussel species in Kendari Bay is not yet fully understood. This study aims to determine the size structure, growth, mortality, and exploitation rate of horse mussels in Kendari Bay. This research was carried out in Kendari Bay on the outskirts of Southeast Sulawesi, Indonesia, from January to December 2019. Horse mussel samples of all different sizes were randomly collected from different points of the area of the mussel habitat. The collected samples were counted in total, and their shell length was measured using a caliper with an accuracy of 0.05 mm. The size, growth, mortality, and exploitation rate data were analyzed using the Bhattacharya method, inverse von Bertalanffy, Pauly empirical, and length-converted catch curve accommodated in the FiSAT II. The results showed that the horse mussels comprised two dominant size groups, with one dominating most of the months. The asymptotic length (L?) of the mussels was 9.7 cm, with a growth coefficient (K) of 1.1 yr-1. Moreover, the growth performance index of the mussels was (Ø)'=2.01 yr-1, and the maximum age (Tmax) was 2.73 years. The generated inverse von Bertalanffy equation for the horse mussels was Lt = 9.7-(9.7-0.025)e-1.1t. The natural mortality (M), fishing mortality (F), and total mortality (Z) of the horse mussels were 2.73 yr-1, 1.17 yr-1, and 3.90 yr-1, respectively. The horse mussels in Kendari Bay were well within the underexploited category, with an exploitation rate of 0.30
