This study assessed the fluctuations of two key indexes - Fulton and Clark indexes - in evaluating the nutritional status and health of Mystus albolineatus at two different sampling sites within the Hau River basin, Mekong Delta. A total of 597 specimens comprising 307 females and 290 males were collected from Cai Rang (Can Tho) and Long Phu (Soc Trang) from January to December (2023). The results indicated that both indexes were not influenced by sex or sampling site but varied significantly according to season and month. The Fulton index was significantly higher during the dry season (1.53±0.03 SE) compared to the wet season (1.35±0.04 SE, F=14.06, pMystus albolineatus, contributing to managing and conserving fishery resources in the Mekong Delta.