Influences of ration level and initial body weight on growth and size hierarchy of hybrid tilapia, Oreochromis mossambicus x O. niloticus
Wang, Y.
Ying Yong Sheng Tai Xue Bao 14(2): 237-240
2003
ISSN/ISBN: 1001-9332 PMID: 12827878 Document Number: 556010
72 hybrid tilapia were distributed into twelve tanks, each stocked in six fish (A, B, C, D, E, F) with different body size. The initial body weight was 62.69 +- 1.46 g for fish A, 56.48 +- 1.30 g for B, 50.75 +- 1.19 g for C, 35.56 +- 1.18 g for D, 31.05 +- 0.88 g for E, and 27.35 +- 0.95 g for F (mean+-SE). The fish were reared under four ration levels (deprived of feed, fed at 1.5% body weight per day (BWcntdotd-1), fed at 3.0% BWcntdotd-1, or fed excess) throughout four weeks, respectively. The specific growth rate (SGR) and feed efficiency (FE) of the fish increased with increasing ration level up to 3.0% BWcntdotd-1 , and then, SGR maintained at a constant level while FE dropped with continuing increase of ration. The variance coefficient of SGR and final body weight was relatively high in the fish that fed at 1.5% BWcntdotd-1. For fish A, SGR was not significantly different, between 1.5% BWcntdotd-1, 3.0% BWcntdotd-1 and fed excess, while in fish F, relatively high variations were found among different ration treatments. This experiment revealed that the growth and size hierarchy of hybrid tilapia were related to their ration level and initial body size. Under ration levels more than 3.0% BWcntdotd-1, SGR was usually high, and size hierarchy was relatively weak.