Setijanto,Yuwono, E, Sukardi P and Sulistyo, I, 2003 STUDY ON FEEDING BEHAVIOUR OF EELS AND THE LARVAE OCCURRENCE IN SEGARA ANAKAN 1 Setiyanto, Edy Yuwono, Isdy Sulistyo and Purnama Sukardi Biology Faculty, UNSOED Purwokerto 53122 ABSTRACT Two species of eels Anguila bicolor and Anguila marmorata were found in Segara Anakan, Cilacap. Feeding behavior of these eels was studied during the rainy season. Gut content was analysed and the ratio of body length and intestine length was calculated. The abundance of the occurrence of eel’s larvae was investigated during ebb and tide. The results showed that the eel is nocturnal and carnivorous. Crustacea, which was abundance in Segara Anakan, seems to be the most important food for both eels, although they also feed on other zooplankton. Correlation between zooplankton abundance and gut content shall be discussed. Larvae of the eels occurred during November and again during March, but not occurred during December, January and February. INTRODUCTION Eels Anguilla sp. have been reported to inhabit Segara Anakan Cilacap, Central Java (Ecology Team, 1984; Tomascik et al., 1997). The present study found two species of eel Anguilla bicolor and A. marmorata in Segara Anakan. Continuous degradation of the habitat and uncontrolled fishing activity threaten the eel population unless any efforts in conservation were constructively undertaken (White et al., 1989; Sastranegara, 1996; Setiyanto and Sahri, 2000; review by Yuwono & Misman, 2000). In order to plan and implement conservation program, we need a proper management, which avoids the possibility of over exploitation of the resource. However, there has not been adequate scientific information that might be used for planning ecologically applicable program, which ensure the sustainability of eel population. 1 Proceeding of Tropical Eel Fishery Resource, BPPT, Ministry of Research and Technology.