This study investigated the watermeal cultivation using different concentrations of hydroponic fertilizer at 0, 0.5, 1.0, and 1.5 ml/l for 20 days in addition to feeding the tilapia fingerlings with a commercial diet (CD) and fresh watermeal (FWM) at ratios of 100:0, 70:30, 50:50, 30:70 and 0:100 for 90 days. The results revealed that watermeal cultivated at 1.5 ml/l (treatment 4) showed the highest growth, while no significant difference (p>0.05) was found when compared to watermeal cultivated at 1.0 ml/l (treatment 3). Watermeal cultivated with the highest level of hydroponic fertilizer resulted in the highest nitrate content at 61.53±0.34 mg/kg of fresh weight, which is higher than a lower one (treatment 3) by about sixfold. The suitable level of hydroponic fertilizer for watermeal cultivation was 1 ml/l of water. The tilapia fish were reared by CD and FWM in combined feeding. Fish cultivated in the control treatment (100% CD feeding) showed the highest growth with no significant difference (p>0.05) when compared to fish cultivated at 70:30 of CD and FWM feeding. The control treatment had the lowest survival rate at 52.00±17.43%, recording a significant difference (p < 0.05) when compared to other treatments. Fish in treatment 2 (70%CD:30%FWM) showed the highest specific growth rate (SGR) as 3.33±0.02 %/day, but no significant difference was detected when compared to 100% CD feeding. Therefore, a combined feeding of 70%CD and 30%FWM was found to be a suitable practice in FWM utilization for rearing the Nile tilapia,  Oreochromis niloticus.