Ontogenetic Variation in the Diet Composition of Glossogobius Giuris from Taal Lake, Batangas, Philippines

Glossogobius giuris is an indigenous fish in Taal Lake and is considered to be very important not only due to its reasonable price but also because unlike any other fish, it contains all the nutrients and essential amino acids. Furthermore, this fish is also suitable candidate for artificial culture in the future. Knowledge on the food habits or diet composition is important in evaluating the feeding success of G.giuris which can lead to successful management of stocks in the future. Based on the relative importance, it was found out that the insect larvae and debris were the most important prey items of the juvenile G.giuris while the nematode was the least important. Among the prey items consumed by the adult G.giuris, crustacean eggs and fish larvae had the highest relative importance while the cladocerans had the lowest importance. This revealed that the small or juvenile G.giuris tended to consume more midge larvae and copepods. The adult fish tended to consume mostly crustacean eggs and fish. The trophic level of the juvenile and adult G.giuris revealed that this fish belongs to the second and third level. Based on the calculated trophic level, it showed that this fish can be carnivore, herbivore and omnivore. Lastly, there was a significant difference in the trophic level of the two groups of G.giuris, the juvenile and the adult.

Keywords: Glossogobius giuris, indigenous fish, Taal Lake, Batangas