The growth and growth models of pond-reared sleepy cod Oxyeleotris lineolatus

The present paper deals with the growth characteristics and life-history pattern of pond-reared sleepy cod(Oxyeleotris lineolatus).A total of 148 specimens were collected from experiment base of Dongguan South China Special Fishery Research Institute from April 2001 to August 2006.The 1 to 6 year old fish was found to have body lengths from 14.50 to 43.12 cm,relative growth in length and weight decreasing with ages.The relationship between total length and body length(LT),body weight(W) and body length(LB) was expressed in two formula LT=a+bLB and W=aLb.Growth rate was calculated using Von Bertalanffy equation,for body length by Lt =L∞[1-e-k(t-t0)] and body weight by Wt=W∞[1-e-k(t-t0)]b.The relative weight growth rates(RGR) were calculated by RGRW=(W2-W1)/(t2-t1)×100%,length relative growth rates(RGR) by RGRL=(L2-L1)/(t2-t1)×100%,growth index(GI) by GI=[(ln L2-ln L1)/(t2-t1)]L1.Results showed that relationship between body length,L(cm),and body weight,W(g) was expressed in W = 0.0186L3.1312(R= 0.9863),relationship between total length,LT(cm),and body length,LB(cm),in LT=1.1385LB+0.8702(R=0.9989).Through observation and statistical analysis of the total catch,the Von Bertalantty equations for the species were as follows: L∞=48.43 cm,W∞=3515.53 g,growth coefficient k=0.3099,Starting point age t0=-0.4826.Lt=48.43[1-e-0.3099(t+0.4826)];Wt=3515.53[1-e-0.3099(t+0.4826)]3.1312,the growth inflection point was at tx=3.2 years,corresponding to Ltx=32.96 cm,and Wtx=1053.93 g.This indicated that the fish had much better gowth in the first 3.2 years than that in the later 3.2 years.Differences in relative growth rate and growth indexes also showed the same trend.It is suggested that the fish be a good canidate for commercial culture in ponds,and have better economic benefits,and the cultivation cycle of 2 to 3 years.Specialized Von Bertalanffy growth formula,generalized Von Bertalanffy growth formula,Logistic growth formula,Gompertz growth formula and grey dynamic growth model were used for fitting the length and weight growth.Specialized Von Bertalanffy growth formula,generalized Von Bertalanffy growth formula,Logistic growth formula,Gompertz growth formula and grey dynamic growth model were used for fitting the length and weight growth.The sum of residual squares were compared with one another and the results show that the grey dynamic growth model is the better precise model to fit the growth,followed by the generalized Von Bertalanffy growth formula.