Diet variation and prey composition of exotic clown featherback, Chitala ornata (Gray 1831) (osteoglossiformes : notopteridae) in Laguna De Bay, Luzon Island, Philippines
2018
Corpuz, Mark Nell Castillo
Diet composition and gut fullness of introduced clown featherback, Chitala ornata (Gray 1831) were assessed from three sampling sites (west, central, and east regions) of Laguna de Bay (Philippines). A total of 203 specimens (10.18–98.5 cm) were collected through the fish trap, seining and gillnet fishing from January to March 2014. Twelve stomachs were empty and excluded from the study. From the 191 stomachs, eleven prey items were identified, with Caridina sp. being the most important prey item by number (83.3 %) and frequency of occurrence (54.4 %). Teleosts prey, particularly an endemic Leiopotherapon plumbeus (Kner 1864) was the most important food item by volume (41.6 %). Index of Preponderance and Index of Relative Importance recognised Caridina sp., and L. plumbeus as the two most important food items (in order of magnitude). Gut fullness was significantly different among geographical sites (P < 0.01), with populations from the central region having the highest prey diversity and teleost prey consumption. An ontogenetic dietary shift was observed, where small-sized C. ornata (≤ 45 cm) consumed mainly on crustaceans, whilst teleosts were the main prey type for larger C. ornata (> 46 cm). The proportional weight of teleost-based diet and diversity of food items increased with C. ornata length.
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