CYBIUM, cilt.26, ss.163-172, 2002 (SCI İndekslerine Giren Dergi)
Vertebrae from 720 Clarias gariepinus from the River Asi were used for the study of age and growth. The population consisted of 0+ - 5 age groups including females to 48.75% in addition to males to 50.83% and the abnormal (intersex) of 0.42%. According to the Von Bertalanffy growth model, length equations obtained for females and males were L-t = 82.94 [1 - e(-0.15(t + 1.72))] and L-t = 85.32 [1 - e(-0.1444(t + 0.69))]respectively. The Von Bertalanffy equations did not fit the data satisfactorily, because there were not enough old fish in the data. The absolute length increments for the major age groups (0-3) were 5.32 cm, 9.74 cm, 8.22 cm and 5.68 cm, 10.11 cm, 8.63 cm for females and males respectively. The weight increments for the major age groups (0-3) for females and males were 48.07 g, 179.41 g, 245.51 g and 50.31 g, 167.19 g, 195.02 g respectively. The relationships between the total length in cm (L) and the weight in g (W) for the female and the male were calculated to be W = 0.010 L-2.90 and W = 0.016 L-2.74 respectively. The condition value of C. gariepinus population was found to be high at young ages (0+ and 1) whereupon the increase to 0.8 was replaced by decline in the River Asi. The monthly fluctuation of the condition of catfish is more related with temperature and feeding. It is observed that C. gariepinus population in the River Asi that have a commercial value is under some stress factor such as lack of water, excessive fishing and pollution.