Abstract

A pilot study was conducted on cobia Rachycentron canadum to determine operating parameters for culture, technical feasibility, and associated challenges in a marine recirculating aquaculture system (MRAS) under local conditions. Juvenile cobia 2.8 ± 0.9 g were imported from Florida, USA and quarantined in three 2800 L circular polyethylene tanks attached to a 680 L mechanical filter filled with 0.34 m3 Kaldness® media, a 680 L sump, two 110W ultraviolet sterilizers and moving bed bioreactors (MBBR) made from a 680 L insulated rectangular polyethylene tank with 0.45 m3 of Kaldness® media. Marine salts and treated tap water were used. Fingerlings were acclimatized, sampled and observed for pathogenic organisms, and fed ad libitum with a larval ration. They were transitioned to a 2-mm Ziegler marine feed at 5% BWD and transferred to a MRAS of 62.2 m3 with five 7,700 L circular polyethylene tanks and one 31,000 L fibreglass tank. Water treatment consisted of a 450W ultraviolet sterilizer, drum filter with 60? screen, a 265 LPM foam fractionator and three MBBR of 2,700 L each filled with 40% Kaldness®. Water quality parameters of temperature, salinity, pH, conductivity and ammonia-nitrogen were measured daily, while nitrite-nitrogen, nitrate-nitrogen and turbidity were measured weekly. The study established that cobia could be grown utilizing sea salts but care should be taken with source of seed stock and pre-treatment of source water. Good fish health management practices, trained technical staff, and good system design are also critical elements for success.

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