Effect of different male and female sex ratio on growth of juvenile blue tilapia Oreochromis aureus (Steindachner 1864)

Blue tilapia is one strain of tilapia potential to be developed. This fish has highly tolerant of low temperatures and salinity. In the development of aquaculture of tilapia, male monosex give higher production than mix male-female culture. This activity aims to determine the growth performance of juvenile blue tilapia reared by different ratio of male and female. The study was conducted for 90 days at the Research Institute for Fish Breeding Sukamandi. The fish used are blue tilapia stocking with the initial weight 32.32±2.34 g. Rearing juvenile of blue tilapia using net 2x1 m2 with stocking density 30 fish per net. The treatment is a difference in the ratio of male and female i.e A (100% male), B (75% male: 25% female), C (50% male: 50% female), D (25% male: 75% female), and E (100% female). The fish were fed with formulated food (32% protein) twice daily as much as 5 % of the biomass. The parameters observed were absolute growth, specific growth rate, daily growth rate, feed conversion ratio and survival rate. The results showed A, blue tilapia with 100% male had highest growth performance, longest and the highest weight i.e 8.33±0.67cm and 136.50± 11.92g; with highest specific growth rate, food conversion and survival rate, i,e 1.76±0.05 weight day-1, 1.52±0,20 and 96.66%. While the lowest growth and feed conversion was D, fish mix culture of blue tilapia (25% male: 75% female). Blue tilapia male 100% monosex is recommended to use in aquaculture because it showed the highest growth with lower feed conversion. Abstrak Ikan nila biru (Oreochromis aureus) merupakan satu jenis ikan yang potensial untuk dikembangkan. Ikan ini memiliki keunggulan toleran terhadap suhu rendah dan salinitas tinggi. Dalam perkembangan budi daya, populasi ikan nila tung-gal kelamin jantan diyakini memberikan hasil produksi lebih baik dibandingkan kelamin campuran. Kegiatan ini bertu-juan untuk mengevaluasi performa pertumbuhan yuwana ikan nila biru yang dipelihara dengan nisbah kelamin jantan dan betina berbeda. Penelitian dilakukan di Balai Penelitian Pemuliaan Ikan Sukamandi selama 90 hari. Ikan yang di-gunakan adalah ikan nila biru dengan bobot awal tebar 32,32±2,34 g. Yuwana nila biru dipelihara di hapa berukuran 2x1 m2 dengan padat tebar 30 ekor per hapa. Perlakuan adalah perbedaan nisbah kelamin jantan dan betina yaitu A (100% jantan), B (75% jantan : 25% betina), C (50% jantan : 50% betina), D (25% jantan : 75% betina) dan E (100% betina). Selama pemeliharaan ikan diberi pakan berkadar protein 32% dengan frekuensi dua kali sehari sebanyak 5% dari bobot ikan. Parameter yang diamati meliputi pertumbuhan mutlak, laju pertumbuhan spesifik, laju pertumbuhan harian, nisbah konversi pakan, dan sintasan. Hasil penelitian menunjukkan populasi ikan nila biru yang dipelihara 100% jantan mempunyai performa pertumbuhan panjang dan bobot tertinggi sebesar 8,33±0,67cm dan 136,50±11,92 g dengan laju pertumbuhan spesifik yang tinggi sebesar 1,76±0,05% bobot hari-1, konversi pakan 1,52±0,20 dan sintasan 96,66%, sedangkan pertumbuhan terendah pada populasi ikan nila biru campuran (25% jantan : 75% betina). Pengguna-an ikan nila biru monoseks jantan 100% dianjurkan untuk digunakan dalam kegiatan budi daya karena mempunyai pertumbuhan tertinggi dengan konversi pakan yang rendah.