Judul: (Zophobas morio) Sebagai Sumber Protein Potensial Dalam Pakan Juvenile Discus (Symphysodon.sp)
Abstrak: Symphysodon sp or discus fish is well known ornamental fish with its elegant shape and eye-catching colour. One of the favourite ornamental fish for fish keeper. This study investigates the potential of superworm meal (SWM) as a source of protein in juvenile discus diets. Three groups of juvenile discus fish with mean initial individual body weight (0.29 ± 0.01) were fed with 3 different formula diet. Three different types of diets were created using two main ingredients in varying percentage of Commercial fish feed and Superworm meal with the ratio such as Diet1 100%:0%, Diet 2 60%: 40% and Diet 3 20%: 80%. The diets were given twice a daily for over 8 weeks. After 8 weeks of research, the result shows that diet 2, which consisted of 40 % of SWM, provides the highest weight gain in juvenile discus fish. However, the lower growth performance of juvenile discus fish was revealed for diet 3 with 80 % of SWM. The survival percentage was 100% for all treatments. This study shows that formula 2 feed can be proposed as an alternative growth formula for discus fish because it has the highest growth performance., Symphysodon sp atau ikan discus merupakan ikan hias yang terkenal dengan bentuknya yang elegan dan warnanya yang menarik. Salah satu ikan hias favorit para pemelihara ikan. Penelitian ini mengkaji potensi superworm meal (SWM) sebagai sumber protein pada pakan diskus juvenil. Tiga kelompok juvenil ikan diskus dengan rata-rata bobot badan awal individu (0,29 ± 0,01) diberi 3 formulasi pakan yang berbeda. Tiga jenis diet yang berbeda dibuat menggunakan dua bahan utama yaitu pakan ikan komersial dan superworm meal dengan ratio persentase yang berbeda, berturut-turut Diet 1 100%:0%, Diet 2 60%: 40% dan (Diet 3) 20%:80. Pakan diberikan dua kali sehari. Setelah dilakukan penelitian selama 8 minggu, didapatkan hasil bahwa pakan 2 yang mengandung 40% SWM memberikan nilai pertambahan bobot badan tertinggi pada juvenil ikan diskus. Namun, pertumbuhan yang lebih rendah terungkap untuk diet 3 dengan 80% SWM. Persentase kelangsungan hidup adalah 100% untuk semua perlakuan. Penelitian ini menunjukkan bahwa pakan formula 2 dapat diusulkan sebagai alternatif formula pertumbuhan ikan diskus karena memiliki performapertumbuhan tertinggi
Keyword: Superworm Meal, Discus Fish, protei, juvenile, Growth rate

Judul: Produktivitas Budidaya Ikan Diskus Symphysodon sp. Pada Rasio Media-Ikan 2 hingga 5 Liter per Ekor
Abstrak: Increasing density will be followed by increasing production if it has a good environment and feed accomplished. The purpose of this experiment was to determine the optimal discus fish Symphysodon sp. production in term of growth, survival rate, feed efficiency and economic aspect. The design of the experiment was randomized complete design with 4 treatments and 3 replications. The discus seeds at average lenght of 2.60 + 0.01 cm and of weight 1.36 + 0.01 g were reared at volume of 60 liters. Tubificide feed was given twice a day at satiation level. 50% of the media in the aquarium was replaced with fresh water daily. The result showed that lowering media-fish ratio affected the weight and the growth, but did not affect the survival rate, the feed efficiency value and the length variety coefficient. Based on economic analyze, the highest gain was achieved by the media-fish ratio of 3 L/fish.
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Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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