Effects Of Habbit Structure And Initial Stocking Density On The Weaning Of Yellowcheek Carp

The waning for fingerling of yellowcheek carp (Elopichthys bambusa R.) were conducted in the net cages. The space size and stocking density are two important variables in aquaculture. The present research aimed to estimate the effects of them on growth, survival and serum biochemical parameters, so as to determine the optimal space size and initial density. The main results of the study were as follows:1. Effects of space size on weaning success and growth of juvenile yellowcheek carp (Elopichthys bambusa)Effects of space size on weaning success rate (WRS), specific growth rate (SGR), coefficient of variation (CV), mortality rate (MR), cannibalism rate (CR) and relevant serum biochemical parameters. Five groups were assigned in the net cages with different space sizes (length×widthxhight):0.5×0.5×0.6 m~3(Sl),1.0×1.0×0.6 m~3(S2),1.5×1.5×0.6 m~3(S3),2.0×2.0×0.6 m~3(S4),3.0×3.0×0.6 m~3(S5) with three replications in each group. The fry (0.64±0.05g) were move into each net cage at stocking density of 500/m-3.The weaning test lasted for 28 days. WSR increased then decreased with the increasing of space size where the WSR of S2 was highest follow by that of S3, with the lowest WSR in S1. MR (30-57 DAH) was highest in S5 and lowest in S3 (p<0.05). CR (30-57 DAH) was increased along with the enlargement of space size. SGR in S1 and coefficient of variation (CV) of body weight in S2, S3 were significantly lower than those in other groups, respectively (P<0.05). It was concluded that the optimum size of net cage for the weaning of juvenile yellowcheek carp was 1.5×1.5×0.6 m~3 based on the comprehensive results of WSR, weaning efficiency and manipulation strength.2. Stocking density on weaning success and growth of juvenile yellowcheek carp (Elopichthys bambusa)Five groups were assigned in the net cages (1.0×1.0×1.0 m~3,0.6 metres underwater) with different initial density 100 ind/m~3 (Dl)、300 ind/m~3 (D2)、500 ind/m~3 (D3)、 700 ind/m~3 (D4)、900 ind/m~3 (D5), with three replications in each group. WSR increased then decreased with the increasing of stocking density. In accordance with regression analysis, relationship between WSR and stocking density based on quadratic regression analysis was:Y=-1.396X2+16.10X+40.36, correlation coefficient:R2=0.935, the optimum density was of 577 ind/m~3. MR decreased and then increased with the addition of stocking density. The quadratic regression analysis was:Y=0.57X2-5.65X+28.27, correlation coefficient:R2=0.789, the optimum density was of 496 ind/m~3. Relationship between CR and breeding density according to linear regression analysis was: Y=1.63X+1.74, correlation coefficient:R2=0.841. SGR decreased with the increasing of stocking density in D2-D5 meanwhile, SGR in D1 was significantly lower than other groups. CV in D1, D2, D5 was significantly higher than D3, D4 whereby D1 highest. Under the conditions of the experiment, the optimal initial density of net cage for the weaning of juvenile yellowcheek carp was 500～700 ind/m~3.