Optimization of salinity range for rearing glass eel Anguilla bicolor bicolor

ABSTRACT Fasting is one of a method that used for measured growth of fish in a shorter period of time. This study was aimed to determine the optimum range of salinity for improve the survival and growth of glass eel Anguilla bicolor bicolor. It used a completely randomized design (CRD) with four salinity treatments and three replications, namely (A) 0 g/L, (B) 10 g/L, (C) 20 g/L, and (D) 30 g/L. The fish used were of glass eel A. bicolor bicolor with 0.15–0.23 g of weight. The experiment was conducted in an aquarium of 60×30×30 cm with a volume of 30 Liters and at a stocking density of 2 g/L for 14 days. During the maintenance, glass eels were fasted for have a significantly of biomass decline. Data collection was done at the start and the end of maintenance. Parameters measured included survival (%) and the rate of decline in absolute biomass (g). Physical and chemical parameters included temperature, dissolved oxygen, and pH which were measured daily, while ammonia and alkalinity were measured every seven days. Result showed that survival was not significantly different between treatments (P>0.05), while the rate of decline in absolute biomass was significantly different between treatments (P<0.05). Treatments of 0 g/L salinity was the lowest survival than the others. While treatment of 10 g/L salinity was the lowest rate of decline in absolute biomass. According to research, the optimum salinity was 10 g/L, and after analysis with quadratic regression analysis, the optimum range of salinity were 5.00–13.40 g/L. Keywords: optimum salinity, survival, growth, glass eel, Anguilla bicolor bicolor ABSTRAK Pemuasaan merupakan salah satu metode pengukuran perubahan bobot ikan yang dipelihara dalam waktu singkat. Penelitian ini bertujuan untuk menentukan kisaran salinitas optimum untuk meningkatkan kelangsungan hidup dan pertumbuhan glass eel Anguilla bicolor bicolor. Rancangan penelitian yang digunakan adalah rancangan acak lengkap (RAL), dengan empat perlakuan salinitas dan tiga ulangan, yaitu (A) 0 g/L, (B) 10 g/L, (C) 20 g/L, dan (D) 30 g/L. Penelitian dilakukan selama 14 hari. Ikan yang digunakan adalah glass eel A. bicolor bicolor dengan bobot 0,15–0,23 g dengan padat tebar 2 g/L. Pemeliharaan dilakukan di akuarium berukuran 60×30×30 cm dengan volume air 30 Liter/akuarium. Selama pemeliharaan glass eel dipuasakan sehingga diperoleh penurunan biomassa yang signifikan. Pengambilan sampel data dilakukan setiap tujuh hari berupa kelangsungan hidup (%) dan laju penurunan biomassa mutlak (g). Parameter fisika kimia air berupa ammonia dan alkalinitas dilakukan setiap tujuh hari, sedangkan suhu, oksigen terlarut (DO), dan pH dilakukan setiap hari. Hasil penelitian menunjukkan bahwa kelangsungan hidup tidak berbeda nyata antar perlakuan (P>0,05) sedangkan laju penurunan biomassa mutlak berbeda nyata antar perlakuan (P<0,05). Berdasarkan hasil penelitian, salinitas 10 g/L, 20 g/L, dan 30 g/L menunjukkan kelangsungan hidup 100%, sedangkan salinitas 0 g/L memberikan kelangsungan hidup terendah. Salinitas 10 g/L menunjukkan pemakaian energi terendah untuk metabolisme tubuh sehingga memberikan penurunan bobot biomassa terendah dibandingkan dengan perlakuan lainnya. Hasil penelitian menunjukkan salinitas optimum adalah 10 g/L, dan setelah dihitung menggunakan analisis regresi kuadratik, maka kisaran salinitas optimum adalah 5,00–13,40 g/L. Kata kunci: salinitas optimum, kelangsungan hidup, pertumbuhan, glass eel, Anguilla bicolor bicolo