<![CDATA[Physical Characteristics of Non-Extruded Floating Fish Feed Produced through Rhizopus oryzae Fermentation ABSTRACTTo reduce the feed production cost of floating fish feed, an innovative method which is cheaper, easier, and simpler compared to the use of extruder machine is needed to provide buoyancy to fish feed. This research was conducted to determine the physical characteristics of floating fish feed prepared through fermention using Rhizopus oryzae on the mixed substrate consisting of commercial sinking fish feed, cassava bagasse, and Lemna minor. The resulting fermented feed was subsequently compared with commercial sinking fish feed in terms of its water stability, absorption, and floatability. The water stability curves of both feed types showed a similar pattern for 20 hours. Both decreased dramatically in the first 0.5 hours, from 100% to 81% for the fermented feed, and to 83% for the commercial feed. The shape of a 40-minute water absorption curve for both feed types was very similar. The fermented feed absorbed water nearly 4 times its initial dry weight, while commercial feed up to about twice as much as its initial dry weight. For three hours, both fermented and commercial floating pellets stayed afloat 100% without sinking. Thus, fermentation using R. oryzae deserves further development as an alternative way to provide buoyancy to fish feed.Keywords: floatability, floating feed, sinking feed, water absorption, water stability ABSTRAKUntuk menekan biaya produksi pakan ikan apung, diperlukan inovasi pengapungan pakan ikan yang lebih murah, mudah, dan sederhana dibandingkan dengan penggunaan mesin ekstruder. Penelitian ini dilakukan untuk mengetahui karakteristik fisik pakan apung hasil fermentasi menggunakan kapang Rhizopus oryzae pada substrat campuran pakan tenggelam komersial, onggok, dan Lemna minor. Pakan fermentasi ini lalu dibandingkan dengan pakan apung komersial dalam hal stabilitas dalam air, absorbsi air, dan daya apung. Stabilitas dalam air kedua jenis pakan memiliki pola yang mirip selama 20 jam. Stabilitas keduanya menurun drastis pada 0,5 jam pertama, dari 100% ke 81% untuk pakan apung fermentasi, dan ke 83% untuk pakan apung komersial. Bentuk kurva absorpsi air selama 40 menit untuk kedua jenis pakan sangatlah mirip. Pakan apung fermentasi menyerap air hampir 4 kali bobot kering awalnya, sedangkan pakan apung komersial hingga sekitar 2 kali bobot kering awalnya. Selama tiga jam, baik pakan apung fermentasi maupun komersial mengapung 100% tanpa tenggelam. Jadi, fermentasi menggunakan R. oryzae layak dikembangkan lebih lanjut sebagai cara pengapungan alternatif pakan ikan.Kata Kunci: daya apung, daya serap air, stabilitas dalam air, pakan apung, pakan tenggelam]]>
