Kabupaten Bulungan memiliki sumberdaya ikan yang potensial dengan berbagai hasil tangkapan salah satunya ikan kakap putih (Lates calcarifer). Kegiatan penangkapan yang dilakukan terus menerus dapat mengakibatkan penurunan populasi ikan kakap putih. Tujuan penelitian ini yaitu menerangkan sex ratio, menjelaskan aspek bioreproduksi meliputi, tingkat kematangan gonad (TKG), indeks kematangan gonad (IKG) dan fekunditas serta menjelaskan aspek makanan dan kebiasaan makan meliputi PILB, ISC dan IRP. Penelitian ini dilaksanakan dari bulan Desember 2021 – Maret 2022 di perairan muara Ancam, muara Bulungan dan muara Mapat sebagai lokasi asal sampel ikan serta Pos pembelian ikan di Kelurahan Selumit Pantai Kota Tarakan sebagai lokasi sampling. Metode penelitian deskriptif kuantitatif dengan pendekatan observasi dan metode pengumpulan sampel secara purposive random sampling. Hasil penelitian menunjukkan dari total 69 sampel memiliki nisbah kelamin 1 : 6,7 dimana sampel jantan lebih dominan tertangkap. TKG kakap putih jantan dominan TKG III dan sampel betina dominan TKG I. Nilai IKG ikan kakap putih jantan 0.009 – 1.032% dan pada sampel betina 0.010 – 0.060%. Nilai fekunditas tidak ada karena tidak ditemukan sampel betina yang memasuki fase matang gonad yaitu TKG III dan IV sehingga tidak ditemukan telur di dalam ovari. Nilai PILB yang didapatkan 100% dengan rata-rata nilai indeks kepenuhan lambung sebesar 0,59% dari bobot tubuhnya. Ikan kakap putih (Lates calcarifer) merupakan ikan karnivora dengan jenis makanan utamanya berdasarkan analisa IRP (Indeks Relatif Penting) yaitu dari kelompok chordata (ikan) sebesar 49,09%, makanan pelengkap yaitu makanan lumat (tidak teridentifikasi) sebesar 25,38% dan udang 24,41%, serta makanan tambahan adalah kerang ulir 0,68%, kepiting 0,28% dan serasah 0,16%.
Kata kunci: Bioreproduksi; Kebiasaan Makan; Ikan Kakap Putih

White snapper is one of the prospective fish resources in Bulungan Regency that can be caught (Lates calcarifer). The population of white snapper may decline as a result of on going fishing operations. The study aimed to explain sex ratio, bio reproductive feature such as fecundity, gonadal maturity index (IKG), and gonadal maturity level (TKG), as well as aspects of food and eating habits such as PILB, ISC and IRP. This study was carried out from December 2021 to March 2022 in the waters of the Ancam, Bulungan and Mapat estuaries, which served as the source of the fish samples, and the fish purchase post in Selumit Pantai Village, Tarakan City, which served as the sampling location. Quantitative descriptive research method was used with observation appproach and sample collection method by purposive random sampling. The findings indicated that 69 samples in total had a sex ratio of 1:6.7, with the male sample being more frequently caught. IKG value of male barramundi 0.009 – 1.032% and in female sample 0.010 – 0.060%. TKG male barramundi dominant TKG III and female samples dominant TKG I. Because there were no samples of females entering the TKG III and IV gonad mature phase, where eggs were produced, the value of fecundity was absent. With an average gastric fullness index value of 0.59% of body weight, the PILB score was 100%. According to IRP (Relatively Important Index) analysis, the main source of food for white snapper (Lates calcarifer) was from the chordata (fish) group at 49.09%, with shrimp coming in at 24.41% and crushed food (unidentified) at 25.38%. there were also 0.68% screw shells, 0.28% crab and 0.16% litter as supplemental foods. Keywords: Bio-reproduction; Eating habit; White Snapper