Addition of Bacillus sp. as a Bioremediation Agent on the Water Quality for Nile Tilapia (Oreochromis niloticus) Fry

Tilapia (Oreochromis niloticus) is a freshwater fish species with high economic value, widely cultivated due to its rapid growth and relatively simple farming practices. However, one of the primary challenges in tilapia aquaculture is maintaining water quality, as poor conditions—resulting from factors such as temperature fluctuations, uneaten feed, and fish waste—can negatively impact fish growth and survival. One promising solution is the use of bioremediation systems, particularly probiotics such as Bacillus sp., to enhance water quality. This study aimed to determine the optimal dosage of Bacillus sp. probiotics as a bioremediation agent to improve water quality, as well as the growth and survival rates of tilapia fingerlings. The experiment used a Completely Randomized Design (CRD) with five treatments (P1: 0 ml/L, P2: 0.5 ml/L, P3: 1 ml/L, P4: 1.5 ml/L, P5: 2 ml/L) and three replications each, totaling 15 experimental units. The procedures included container preparation and water conditioning, acclimatization of test animals, probiotic application, water exchange and siphoning, feeding, and water quality monitoring. The best results were observed in treatment P4 (1.5 ml/L), with an absolute length increase of 4.15 cm, absolute weight gain of 3.49 g, a specific growth rate (SGR) of 3.24%/day, and a survival rate of 84.2%.