Apparent nutrient utilization and metabolic growth rate of Nile tilapia, Oreochromis niloticus, cultured in recirculating aquaculture and biofloc systems

Introduction - Recirculating aquaculture systems (RAS) and biofloc systems (BFS) have been considered eco-friendly aquaculture technologies in the last few decades. However, which system performs better has become a common question for fish farmers. Thus, this study aimed to compare the performances of the two aquaculture systems in culturing Nile tilapia, Oreochromis niloticus, larvae. Materials and methods - The experiment was conducted by culturing 3-day post-hatching (dph) tilapia larvae in either the RAS or BFS for 43 days. At the end of the culture period, apparent net protein utilization (NPUa), apparent fat utilization (NFUa) and apparent net energy utilization (NEUa), metabolic growth rate (GRmet) of Nile tilapia, and water quality were compared using analysis of variance. Results - The result showed, in general, that RAS performed better than BFS. NPUa and NEUa were significantly higher in Nile tilapia cultured in RAS than that of BFS, p < 0.05. While NFUa was not significantly different, p > 0.05. GRmet of tilapia cultured in BFS was higher in the first week but showed to be the same during the second week to the fourth week. At the end of the culture period (43 days), the GRmet of tilapia cultured in RAS was significantly higher than those of fish raised in the BFS. Other results showed that water quality parameters, including total ammonia nitrogen (TAN-N) and nitrite nitrogen (NO2-N), were lower in RAS than in BFS during the culture periods. While urea and CO2 were significantly higher in the rearing water of BFS than that of RAS, p < 0.05. Conclusion - The RAS had better performance than the BFS in culturing tilapia larvae.