THE ABUNDANCE AND UTILIZATION OF NATURAL LIFE FOOD IN PONDS FOR ASIAN CATFISH Pangasianodon hypophthalmus LARVAE REARING
Generally, Asian catfish larvae rearing was conducted in indoors hatchery for the first 30 days. In that period, the larvae were fed with Artemia nauplii at the first week, followed by Moina, Daphnia, Tubivex and artificial powder feed at the last time. However, since Artemia cyst price is quite high and it requires some specialised facilities to produce, it will be a constrain in development of the Asian catfish hatcheries. This study was conducted to evaluate the outdoor rearing system for Asian catfish larvae, especially the abundance and utilization of natural life food in ponds for substitute the using of Artemia cyst.
Three fertilized ponds with size 200 m2 were prepared, followed the standart operational procedure for pond preparation in Asian catfish larvae rearing. Natural life food in ponds was identified at the 10th days after fertilization. The larvae at the age of 5 days after hatching was used as the test fish. Natural food in the abdomen and digesty tract of fish were identified in the 2nd day after the fish stocked in ponds.
The results showed that the index of diversity, index of uniformity and index of dominancy for phyto and zooplankton which found in ponds ranged from 2.407 to 2.732; from 0.032 to 0.043 and from 0.112 to 0.204, respectively. Based on the digestive tract of fish analysis, there are found that index of selectivity and index of preponderance for natural life food were ranged from 0.94 to 0.62 and from 0.17 to 67.03, respectively. After 60 days rearing period in ponds, the individual body weight, survival rate and the biomass of fish were ranged from 9.81 to 12.32 g; from 54.53 to 71.49 % and from 118.77 to 141.91 kg, respectively. Based on this study, rearing of Asian catfish larvae can be conducted in ponds at the age of 5 days after hatching. Utilization of the natural life food in ponds subtitutes the using of Artemia cyst in indoor hatchery system.