Abstract : Humpback grouper (Chromileptes altivelis) is sensitive to stress that caused low growth rate, mortality, and harvest. Iron is micronutrient that can enhance the immunity. This experiment was conducted to determine the iron supplement in the feed for humpback grouper fish to vitality increase at hypoxia stress condition. The fish weight 4.14?0.01 g/ind. and was cultured in 60?40?50 cm aquarium and stocked at a density of 10 ind./aquarium. Aftr reared for 61 days, the fish was fed by diet that contained inorganic-iron supplementation at 0, 50, 100, and 200 ppm respectively. The feed was given three times daily at a satiation. The fish was exposed two hours during hypoxic condition and the rearing period were 25 days at normoxia. The results of this study showed that growth performance of fish not significantly different among iron supplement levels, but during and after hypoxia exposure, 50 ppm Fe supplement in the diet of humpback grouper showed the most vitality and healthy condition of fish, while the survival rate of fish was 100% and the growth relative was 82%. However, the humpback grouper fish grew negatively if iron supplement in the diet was more than 50 ppm.

Abstrak : Ikan kerapu bebek (Cromileptes altivelis) rentan terhadap stres sehingga menyebabkan pertumbuhan rendah, kematian, dan penurunan produksi. Zat besi (Fe) merupakan salah satu mikro-nutrien yang mampu meningkatkan daya tahan tubuh. Penelitian ini dilakukan untuk menentukan level penambahan Fe dalam pakan ikan yang mampu meningkatkan vitalitas kerapu bebek saat kondisi stres hipoksia. Ikan yang digunakan berbobot awal rata-rata 4.14?0.01 g, dipelihara pada akuarium berukuran 60?40?50 cm dengan kepadatan 10 ekor/akuarium. Selama pemeliharaan 61 hari, ikan diberi pakan tambahan Fe-anorganik 0, 50, 100, dan 200 ppm, tiga kali sehari secara at-satiation. Ikan diberi stres hipoksia selama 2 jam, dan dipelihara kembali pada kondisi oksigen normal selama 25 hari. Hasil penelitian menunjukkan performan pertum-buhan ikan kerapu bebek sama untuk 3 level Fe berbeda. Namun, pada saat dan sesudah pengujian hipoksia, penambahan supplementasi Fe 50 ppm dalam pakan menunjukkan vitalitas dan kesehatan ikan kerapu bebek tertinggi dengan laju sintasan (survival rate) 100% dan pertumbuhan relatif mencapai 82%, tetapi penambahan Fe di atas 50 ppm berdampak negatif pada pertumbuhan ikan kerapu bebek.