This study was carried out in four sites along the coastline of the Mekong Delta, including Duyen Hai - Tra Vinh, Tran De - Soc Trang, Dong Hai - Bac Lieu, and Dam Doi - Ca Mau, in order to provide knowing morphometrics and meristics variation of Butis butis - a commercial fish in the Mekong Delta, Vietnam. Seven hundred fifteen individuals fish (412 males and 303 females) were collected from March to August 2019 using trawl nets. The study results showed that the total length (TL) and weight (W) of this species were stable by gender and season but fluctuated widely between study sites. Similarly, some other morphometrics of B. butis such as eye diameter (ED), eye distance (DE), body height (BD), head length (HL) did not fluctuate by gender and season but fluctuated by study site. Besides, meristics of this fish like ED/HL, DE/HL, BD/TL and HL/TL also did not fluctuate by gender and season but fluctuated by study site. The results also showed that DHTV (the point with the lowest salinity) is the most appropriate point for the morphological development of this species. Besides, morphological changes in different environments took place in all morphological indicators of this fish. The study has provided essential data on the morphological changes of this fish species in the coastal provinces of the Mekong Delta. The findings are the basis for further studies, especially genetic studies of this fish in the future.