EXPERIMENTS AND OBSERVATIONS ON PREY SELECTION, CONSUMPTION AND STARVATION IN Chitala ornata (Clown Knifefish), AN INVASIVE PISCIVOROUS SPECIES IN LAGUNA DE BAY

Prey size selection, consumption and the ability to withstand starvation were studied in piscivorous predatory Clown knifefishes from Laguna de Bay, Philippines. The findings of the experiment on prey size selection indicate that all the size classes of Chitala ornata preferred to eat small and medium sized Gambusia affinis instead of larger sized prey. For daily prey consumption, the small, medium, and large Clown knifefishes consumed an average of 4.11 g, 7.06 g, and 10.10 g respectively. The large size class of Chitala ornata has the greatest increase in weight with an average of 142.83 g whereas the small and medium Chitala ornata has an average weight increase of 87.98 g and 75.98 g respectively. The % change in weight indicates that the small Chitala ornata has the highest % weight gain of 254.1 followed by the medium (96.9%) and lastly, the large size class (87.6%). Experiments on starvation show that the medium Chitala ornata has the smallest actual weight loss per week of 36.5 g, followed by the small (58.8 g) and large (64.0 g) Chitala ornata . Based on the % weight loss in the three size classes of Chitala ornata , the small size exhibited the highest % weight loss of 41.5 whereas the medium and large Chitala ornata have a lesser % weight loss of 19.4 and 21.4 respectively.