Water improvements in aquaculture are among the critical solutions to remove ammonia resulting from biological processes. In this study, t algae Chlorella vulgaris was used to remove ammonia from the fish farm water of catfish Clarias garepienus. Ammonia chloride was used with algae to study the response by algae to the removal rates of ammonia and the best concentration of alga. The concentration and time rates were then used in the aquaculture, in addition to measuring the water's improvement rate again. The results revealed that the improvement and treatment of variable ammonia concentration (NH4+) by using a volume of algae C. vulgaris (350 ml) recorded the highest percentage (75%) at ammonia concentration (10 mg L−1). Approximately 60% of ammonia were removed (30 mg L−1). When applied to the water fish farms for 24 and 48 h, the ammonia concentration (NH4 +) was markedly decreased from 10 mg L−1 to 3.7 mg L−1 (63%) and 2.3 mg L−1 (77%) after 24 h and 48 h, respectively. Through applied on the fish pond, noted reduced the water used by 60% compared to the control pond. It was observed that most of the items positively influenced by algae were mainly implemented, including ammonia and other elements. This implementation is recommended in intensive aquaculture to improve the water quality and reduce the operating costs in water usage and expected wast water recycling towards achieving progress and sustainable development.