The effects of stocking densities on the growth performance of bong-lao fingerling (Pangasius krempfi Fang & Chaux, 1949) raised in cages placed in earthen pond at Ben Tre province
Abstract
This study was conducted to determine the appropriate density for the growth of Pangasius krempfi fingerling. The fingerlings (length 46.0±7.0 mm and weight 1.4±0.6 g) were collected from exploitation fingerling households and randomly released in cages (60 m2) put in earthen ponds (1,500 m2/pond) at densities of 20, 30, and 40 ind/m2, corresponding to three treatments, each treatment was repeated 3 times. During the rearing period, the fingerlings were fed industrial feed containing 44-55% protein, 2 times/day. After 35 days of rearing, results showed that the daily growth length rate in the treatments was 1.33±0.07 mm/day (1.99±0.06%/day); 1.30±0.09 mm/day (2.01±0.13%/day); 1.28±0.11 mm/day (1.94±0.09%/day) (p>0.05), respectively; and the daily growth weight rate were 281.6±17.5 mg/day (5.84±0.12%/day), 257.9±30.6 mg/day (5.83±0, 32%/day) and 242.6±52.9 mg/day (5.45±0.31%/day) (p>0.05), respectively. The coefficient of variation of length and weight at different densities were15.8±1.0% and 42.9±3.2%, respectively (20 ind/m2); 17.6±2.8% and 49.1±8.4% (30 ind/m2); 15.4±1.3% and 46.5±6.3% (40 ind/m2). The highest survival rate achieved at the density of 20 ind/m2 was 91.0%, statistically significant difference (p<0.05) compared to the remaining densities of 30 ind/m2 (55.1%), and 40 ind/m2 (39.6%). From the research results, it can be seen that, in the experimental densities, the appropriate stocking density of bong-lao fingerlings is 20 ind/m2.
