The Israeli Journal of Aquaculture Bamidgeh 57(4), 2005, 241-249
 
EFFECTS OF FLOW VELOCITY ON GROWTH OF JUVENILE COBIA (RACHYCENTRON CANADUM)

Shyi-Liang Yu1* and Ping-Sheng Ueng2

1Department of Leisure Management, National Penghu University, Makung, Penghu 880, Taiwan
2 Department of Aquaculture, National Penghu University, Makung, Penghu 880, Taiwan
 
(Received 23.3.05, Accepted 26.6.05)

Key words: cage aquaculture, cobia, flow velocity, growth, Rachycentron canadum
 
 
Abstract



The objective of this study was to investigate the growth rate and feed conversion ratio (FCR) of juvenile cobia, Rachycentron canadum, in different flow velocities. In experiment A, fifteen groups of fish with an initial mean weight of 14.35 g were reared for 28 days in one of five flow velocities: 0, 5, 10, 15, and 20 cm/s. In experiment B, fifteen groups of fish with an initial mean weight of 30 g were reared for 21 days in the same velocities as in experiment A. In experiment C, fish weighing an average 77 g were raised for 21 days in 0, 10, 20, 30, and 40 cm/s. The optimal velocities in terms of growth rate were 10 cm/s for fish of 10-30 g (experiment A), 20 cm/s for fish of 30-60 g (experiment B), and 23 cm/s for fish of 60-200 g (experiment C); the optimal velocity increased as the fish weight increased. FCR and specific growth rate (SGR) also significantly ( p<0.05) corresponded to the flow velocity for the different sized juveniles with the optimal FCR and weight gains occurring at 10-23 cm/s. FCR rapidly increased when the velocity exceeded 35 cm/s, regarded as the maximum flow velocity for fish growth.

* Corresponding author. Tel.: +886-6-926-4115 ext. 1801, fax: + 886-6-9277290, e-mail: slyu@npu.edu.tw

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