Abstract: To determine the age structure and growth characteristics of Clarias gariepinus, sagitta ray sections, body length and weight were examined using 223 specimens collected in South China during August 2011 and June 2015. These specimens were comprised of 3 age groups ranging from age 1 to age 3. Additionally, the dominated age was age 1, accounting for 60.19% of the total specimens. The formulas of the relationship between standard body length (L) and total weight (W) for females and males were W_♀=5.763×10^-5 L^2.737 (n=87, R²=0.989),W_♂=9.239×10^-5 L^2.631 (n=122, R²=0.942), respectively, which showed that the growth of C. gariepinus was nearly isometric. The growth pattern of C. gariepinus was formulated by Von Bertalanffy growth function as follow: L_t=455.566(1-1877.112e^-8.036t)， W_t=1089.19(1-1877.112e^-8.036t)^2.737 for females and L_t=475.187(1-1.48e^-0.908t）， W_t=1019.66(1-1.48e^-0.908t）^2.631  for males. The growth inflection points for females and males were 1.07 and 1.64 respectively when the corresponding standard body lengths on the growth infection points were 297.75 mm for females and 316.79 mm for males, and the corresponding total weights were 340.08 g for females and 350.88 g for males. Analysis also showed that the growth rate became lower with the increasing age, and the younger matured individuals grow faster than the older ones. Our results suggested that C. gariepinus has a large population size with single age structure in South China. Moreover, C. gariepinus population is in the rapid growth period, and is likely to burst into a sudden growth in the South China.

Key words: landscape change, Dongzhai Harbor, mangrove, patch-based analysis.