Fish migrations are an important characteristic of the Ayeyarwady River, Myanmar. There are estimated to be 600 species in the basin, and all need to move between critical habitats to complete their life cycle. Unfortunately, migration behaviors of most fish species are poorly understood. Without greater knowledge, many migratory species are threatened by hydropower and irrigation dams by blocking their migration routes and altering flow patterns. To address these critical knowledge gaps, Catfish species (Pangasius pangasius and Pangasius sp.) were collected from a range of environments in the Ayeyarwady River, to examine their life history. An otolith microchemistry approach (Laser Ablation – Inductively Coupled Plasma Mass Spectrometry and Scanning X-ray Fluorescence Microscopy) was used to determine natal origin of multiple species. Ratios of otolith Sr:Ca and Ba:Ca are used as proxies to reconstruct their historical habitat experiences across salinity. Our results suggested that most of these catfish regularly migrate between freshwater and marine waters. Therefore, any activity disrupting these migratory pathways and disconnecting these environments must be carefully considered.