Evaluation of Water Quality Management Practices in Recirculating Aquaculture Systems in Abuja, FCT

Recirculating aquaculture systems represent an intensifying segment of urban fish production in Nigeria's Federal Capital Territory, yet the water quality management practices of operators in this technology-intensive sector have not been systematically evaluated. This study assesses the water quality management practices, monitoring frequency, treatment system performance, and operational challenges of 20 recirculating aquaculture system operators in Abuja and its environs. Data were collected through structured operational audits, water quality measurement at system components, and interviews with farm managers. Water quality parameters monitored included dissolved oxygen, total ammonia nitrogen, nitrite, nitrate, pH, temperature, total suspended solids, and turbidity at system inlet, biofilter effluent, and tank outlet points. Results revealed that 65% of systems recorded ammonia nitrogen concentrations exceeding the recommended safe limit for tilapia (0.1 mg/L) at least once monthly, attributed primarily to biofilter immaturity or overloading. Only 40% of operators conducted daily dissolved oxygen monitoring, and only 25% tested for nitrite more than once per week. Dissolved oxygen saturation in fish tanks averaged 72% across all systems, below the 80% recommended for optimal tilapia growth. Biofilter performance was the parameter most strongly associated with overall system productivity. The study recommends the development of a standardised recirculating aquaculture system monitoring protocol for operators in Abuja and the establishment of a technical support network connecting system suppliers with farm managers.

Keywords: recirculating aquaculture systems, water quality management, biofilter, ammonia nitrogen, Abuja FCT