Speakers
Description
Despite the advancements in recirculating aquaculture system (RAS) technology, there has been limited research on systematically evaluating how biofilter volume scaling impacts water quality and fish performance in medium-scale operations. This study addresses that gap by comparing two RAS designs for African catfish (Clarias gariepinus) culture. The research specifically evaluated a conventional 20L biofilter system against a 70L biofilter system in identical 14-ft diameter pond configurations.
Two RAS systems were established using circular tarpaulin-lined ponds (~13m³ volume each) and were stocked with 1000 catfish fingerlings (12.8g ± 0.4g initial weight). Both systems used identical components for aeration and filtration, with the only difference being the biofilter volume. Water quality and fish growth metrics, including length, weight gain, survival rate, feed conversion ratio (FCR), and specific growth rate (SGR), were monitored over a 16-week production period. A randomized complete block design with three replicates was used for statistical analysis.
The improved biofilter system (RD2) consistently outperformed the conventional design (RD1) across all metrics. The catfish in RD2 demonstrated a 16% greater weight gain (0.15kg vs. 0.13kg), a 4% higher length increment, and a higher survival rate (>98%) at the end of the trial. This enhanced growth was due to a higher SGR and a lower FCR, which indicates superior nutrient utilization and metabolic efficiency. While both systems maintained acceptable dissolved oxygen and temperature levels, the RD2 system provided a more stable environment with a consistently favorable pH (6.7-7.8).