Development and on-farm demonstration of a simplified multi-stage biofiltration system for hybrid catfish recirculating aquaculture

Information from the abstract

Investment and operational requirements can constrain the adoption of recirculating aquaculture systems (RAS) by small-scale freshwater farmers. This 77-day on-farm evaluation assessed the operational feasibility of a simplified RAS comprising one sedimentation tank, one bioball biofilter, two volcanic-rock biofilters, and a single 75-W pump for hybrid catfish (bighead catfish, Clarias macrocephalus Günther, 1864× North African catfish, Clarias gariepinus (Burchell, 1822)) production. One 3-m3 RAS pond and one conventional pond were evaluated under commercial farming conditions. Compared descriptively with the conventional pond, the RAS produced a higher observed final mean body weight (113.40±8.12 vs. 82.60±17.55 g fish-1), average daily gain (ADG, 1.29 vs. 0.89 g fish-1 day-1), specific growth rate (SGR, 2.71 vs. 2.30% day-1), estimated survival (98.33 vs. 94.17%), and harvested biomass (53.52 vs. 37.35 kg pond-1), together with a lower apparent feed conversion ratio (1.19 vs. 1.54). The RAS had higher mean dissolved oxygen (DO) and lower mean chemical oxygen demand (COD). However, ammonia nitrogen and nitrite nitrogen were also higher, indicating that nitrogen conversion did not consistently match the system load. Excluding initial pond filling, the RAS required 74.17% less freshwater and achieved approximately 5.6-fold greater water-use efficiency (1.17 vs. 0.21 kg harvested biomass m-3 freshwater). The incremental component investment was 6,800 THB, while the combined freshwater and recirculation-energy cost was lower under the tariffs applied. Because each system was represented by only one pond, the results constitute a descriptive operational comparison rather than statistically replicated evidence of treatment effects. The developed RAS shows practical potential for reducing freshwater demand in hybrid catfish production, but optimization of nitrogen conversion remains necessary. Replicated multi-cycle and multi-farm evaluations are required to confirm its production performance, long-term reliability, and economic feasibility.

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Related topics: Innovations in Aquaponics and Hydroponics Systems · Aquaculture Nutrition and Growth · Fisheries and Aquaculture Studies