The study aimed to investigate water quality parameters and diatom species composition in super-intensive whiteleg shrimp ponds. The study was carried out at shrimp farms in Bac Lieu city, Bac Lieu province. A total of 11 sampling times, which were divided into 2 periodsincluding rearing phase (2 ponds) and tgrow-out phase (4 ponds) were conducted. The results indicated that water quality parameters varied widely during the culture cycle, in which nutrient concentrations (TAN, NO3 - , and PO4 3- ) tended to increase toward the end of the crop. A total of 16 algal species were recorded in shrimp ponds. Diatoms had the highest species composition (8 species, 50%), and the others ranged from 2 to 3 species (12-19%). Average diatom densities were 2,813,930 ind. L-1 and 2,614,583 ind. L-1 in the rearing and grow-out periods, respectively. Thalassiosira sp. had a very high occurrence frequency and domination (84- 99%) throughout the sampling stages. The diatom species included Thalassiosira sp., Cylindrotheca closterium, Nitzschia sp., Amphiprora alata, Navicula sp., Pleurosigma sp., Chaetoceros sp., and Coscinodiscus sp. These findings are valuable for the proper management of algae in brackish water shrimp ponds.