The Duckbill sleeper Butis butis (Hamilton 1822, Eleotridae) is an important fish for food in the Mekong Delta, Vietnam; however, information on the fish length and weight relationship (LWR) and growth pattern have not been known. The present study was conducted in Nha Mat and Ganh Hao, Bac Lieu to contribute fundamental knowledge on LWR and growth pattern of this goby. Data analysis based on a total of 141 individuals fish were caught by gill nets from June 2015 to May 2016 showed that male B. butis outnumbered females. The mean length of males (10.28±0.25 SE) was not significantly different from its counterpart (10.29±0.39 SE). Similarly, average weight of males (13.04±1.08 SE) was near to females (13.70±1.59 SE). The fish weight could be estimated from fish length because of due to high determination values of LWRs. It displayed negative allometric growth since its slope value was lower than the standard threshold (b = 3)