PENGARUH LAMA PERENDAMAN DALAM HORMON METIL TESTOSTERON (MT) ALAMI TERHADAP JANTANISASI LARVA IKAN NILA (Oreochromis niloticus) ABSTRAK Tujuan penelitian ini adalah mengetahui pengaruh lama perendaman dalam hormon metil testosteron (MT) alami terhadap jantanisasi larva ikan nila (Oreochromis niloticus). Penelitian ini dilaksanakan di kampung Lamdingin, Banda Aceh dari bulan Desember 2013-Maret 2014. Penelitian ini menggunakan 360 larva ikan nila berumur 7 hari dari Balai Budidaya Air Payau, Ujung Batee. Banda Aceh, yang dibagi atas 4 kelompok perlakuan dan 3 kali ulangan. Kontrol (P0), perendamandalam larutan MT alami selama 10 jam (PI), 20 jam (PII), dan 30 jam (PIII). Larva ikan nila dipelihara sampai umur 60 hari kemudian dilakukan pengamatan jenis kelamin ikan. Rata-rata persentase ikan nila berjenis kelamin jantan pada kelompokkontrol (P0),yaitu 50,28%, kemudian diikuti oleh kelompok perendaman 10 jam (PI) sebesar 87,77%, kelompok perendaman 20 jam (PII) sebesar 90.06%, dan kelompok perendaman 30 jam (PIII) sebesar 95,05%. Hasil analisis statistik tidak terdapat perbedaan secara nyata (p>0,05) antara PI, PII, dan PIII. Dapat disimpulkan bahwa lama perendaman tidak berpengaruh terhadap persentase keberhasilan proses jantanisasi ikan nila. The effect of dipping time in natural methyl testosterone hormone on masculinization of tilapia larvae (Oreochromis niloticus) ABSTRACT The purpose of this research is to know the influence of dipping time in natural methyl testosterone hormone (MT) on masculinization of tilapia (Oreochromis niloticus) larvae. This research was carried out at Lamdingin village, Banda Aceh from December 2013-March 2014. This research used 360 tilapia larvae with the age of 7 days. Purchased from Cultivation of brackish water, Ujung Batee. Banda Aceh. The samples were devided into 4 treatment groups with tree repetition. Groups one (P0) control group without treatment, group two (PI), three (PII), and four (PIII) were dipped in asolution of natural MT for 10, 20, and 30 hours, respectively. Tilapia larvae were maintained until the age of 60 days, then the sex of the fish were examined. The average percentage of male tilapia in group P0, PI, PII, and PIII were 50.28%, 87.77%, 90.06%, and 95.05%, respectibely. The statistical result showed that there were ni significant differences (p>0,05) between PI, PII, and PIII. It can be concluded that the longest dipping time is not affect the percentage of masculinization of tilapia.