Journal of Marine and Aquatic Sciences 6(1), 118-124 (2020) doi: https://doi.org/10.24843/jmas.2020.v06.i01.p14 J. Mar. Aquat. Sci. 6: 118-124 (2020) The Competition among Fish Species Based on Types of Food in Buyan Lake, Bali, Indonesia Ni Wayan Shanti Paramita Jayanti a *, Pande Gde Sasmita Julyantoro a , Gde Raka Angga Kartika a a Program Studi Manajemen Sumberdaya Perairan, Fakultas Kelautan dan Perikanan, Universitas Udayana, Jimbaran, Badung, Bali-Indonesia * Penulis koresponden. Tel.: +62-8585-7622-167 Alamat e-mail: shantiparamita1996@gmail.com Diterima (received) 11 Mei 2018; disetujui (accepted) 21 September 2020; tersedia secara online (available online) 22 September 2020 Abstract Buyan Lake is located in Bali Province, this lake has a variety of fish species which several of those species are introduced species that called as alien fish. The relationship interaction between native fish and introduced fish can be described based on the study of food habit and competition of food types. The study was conducted from January to March 2018. Types of fish caught in Buyan Lake during the study were 7 species of fish namely Oreochromis niloticus, Amatitlania nigrofasciata, Osteochilus vittatus, Cyprinus carpio, Xiphophorus hellerii var. 1, Xiphophorus hellerii var. 2, and Rasbora lateristriata. The results showed that the fish with the highest ISC value was Amatitlania nigrofasciata, while the fish with the lowest ISC (Index of Stomach Content) value was Xiphophorus hellerii var. 1. The standard deviation range of almost all fish species is close to zero, so it is suspected that the contents of the stomach are nearly similiar. Amatitlania nigrofasciata with the highest standard deviation values are thought to have a variety of gastric contents. Based on the analysis of the contents of the stomach content, Oreochromis niloticus, Osteochilus vittatus, and Xiphophorus hellerii var. 2 are belonging to herbivorous fish. While Amatitlania nigrofasciata, Cyprinus carpio, Xiphophorus hellerii var. 1, and Rasbora lateristriata are belonging to omnivorous fish, which are tending to herbivores. The competition of food type is quite strict, there is similarity of food among species of fish in Buyan Lake, which is mean that they are fighting over the same food resources. Keywords: Buyan Lake; fish; food habit Abstrak Danau Buyan terletak di Provinsi Bali, danau ini memiliki jenis spesies ikan yang beranekaragam dengan beberapa spesies ikan merupakan ikan asing. Hubungan interaksi antara ikan asli dengan ikan introduksi dapat dideskripsikan berdasarkan kajian kebiasaan makannya dan bagaimana persaingan jenis makanannya. Penelitian dilakukan dari bulan Januari-Maret 2018. Pengamatan dilakukan pada lambung ikan. Jenis ikan yang tertangkap di Danau Buyan selama penelitian adalah 7 jenis ikan yaitu Ikan Nila (Oreochromis niloticus), Ikan Zebra Cichlid (Amatitlania nigrofasciata), Ikan Nilem (Osteochilus vittatus), Ikan Mas (Cyprinus carpio), Ikan Platy Pedang varian 1/ Nyalian Srembeng (Xiphophorus hellerii var. 1), Ikan Platy Pedang varian 2/ Nyalian Mas (Xiphophorus hellerii var. 2), dan Ikan Wader/ Nyalian Buluh (Rasbora lateristriata). Hasil penelitian menunjukkan bahwa Ikan dengan nilai ISC tertinggi adalah Ikan Zebra Cichlid, sedangkan ikan dengan nilai ISC terendah adalah Ikan Platy Pedang varian 1. Kisaran standar deviasi hampir seluruh jenis ikan mendekati nol atau kecil, sehingga diduga isi lambungnya seragam. Ikan Zebra Cichlid dengan nilai standar deviasi tertinggi diduga memiliki isi lambung yang beragam. Berdasarkan analisis isi lambung, Ikan Nila, Ikan Nilem, dan Ikan Platy Pedang varian 2 termasuk ikan herbivora, sedangkan Ikan Zebra Cichlid, Ikan Mas, Ikan Platy Pedang varian 1, dan Ikan Wader termasuk ikan omnivora cenderung herbivora. Persaingan jenis makanan cukup ketat, terdapat kemiripan jenis makanan antar spesies ikan di Danau Buyan atau dengan kata lain saling memperebutkan sumber daya makanan yang sama. Kata Kunci: Danau Buyan; ikan; kebiasaan makan