Fenomena Pertumbuhan Compensatory dan Kualitas Ikan Nila Merah (Oreochromis sp.) pada Kondisi Laut

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Penelitian skala laboratorium untuk mengevaluasi fenomena pertumbuhan compensatory dan kualitas produk (body composition) dari nila merah (Oreochromis sp.) yang dipelihara di air laut dilakukan pada awal Juni sampai awal Agustus 2003 di Hatchery Kampus Kelautan Teluk Awur Jepara FPIK UNDIP. Benih ikan (37,74gr + SD 1,16gr) sebelumnya diaklimatisasikan pada kondisi laut dan dipelihara dalam bak-bak percobaan dengan kepadatan 5 ekor/m3. Perlakuan pemuasaan dengan 3 kali ulangan selama 4 minggu percobaan, yaitu: ikan diberi pakan setiap hari (A/kontrol); diberi pakan selama 6 hari diikuti pemuasaan 1 hari (B); diberi pakan selama 5 hari diikuti pemuasaan 2 hari (C); dan, diberi pakan selama 4 hari diikuti pemuasaan 3 hari (D). Pakan berbentuk pellet tenggelam (PT CP Prima) dengan kandungan protein 24-26%, lemak 3-5%, serat kasar 4-6%, abu 5-8% dan air 11-13%, diberikan 2 kali sehari sebanyak 5% dari biomassa. Pengamatan pertumbuhan dilakukan seminggu sekali. Analisa body composition dilakukan untuk mengukur kandungan protein, lemak, karbohidrat dan air (%). Hasil penelitian memperlihatkan bahwa tidak terjadi perbedaan dalam pertumbuhan selama percobaan; hal ini menunjukkan terjadi fenomena pertumbuhan compensatory. Tingkat pertumbuhanpada masing-masing perlakuan yaitu 7,42 gr/minggu (A); 7,18 gr/minggu (B); 3,44 gr/minggu (C); dan, 5,34 gr/minggu (D). Analisis body composition tidak menunjukkan adanya perbedaan dalam kandungan protein, lemak, karbohidrat, maupun air. Kandungan protein normal (>18%). Kandungan lemak rendah, 1,50-1,80%, diikuti kandungan air yang tinggi (>70%), yang menyebabkan tekstur daging lebih lunak. Kandungan karbohidrat 2,7-4,8%.Kata kunci: nila merah, pertumbuhan compensatory, kuantitas, kualitasThe study to evaluate both compensatory growth phenomenon occurred and the fish quality (body composition) were done under the laboratory conditions from beginning June to beginning August 2003 at the hatchery of Marine Science Teluk Awur-Jepara Campus, Diponegoro University. Red tilapias of mean weight of 37.74g+SD 1.16 g were acclimated in seawater conditions. The fish were cultured in the tank with a density of fivefish/m3 The treatments were feeding daily (A/control); fish fed 6 days–a day unfed (B); fish fed 5 days-2 days unfed; and fish fed 4 days-3 days unfed (D). The food was slowly sinking type (CP Prima) containing protein24-26%, oil 3-5%, fibre 4-6%, ash 5-8%, and water 11-13%. Feeding frequency was twice a day with 5% of the biomass. Growth was measured weekly. For fish quality analysis (body composition), it was done tomeasure the contents of protein, fat, carbohydrate, and water (%). The result showed that there was no significant difference of the growth among the fish (ANOVA); and, in turn, it suggested that the compensatorygrowth was occurred. The growth rates were 7.42 g/week (A), 7.18 g/week (B), 3.44 g/week(C), and 5.34 g/week (D). There was no difference for the contents of protein, fat, carbohydrate, and water. In general, theprotein content was above 18%.The low fat contents (1.50-1.80%) was followed by the high water contents (>70%), so that it made the flesh texture being soft. The carbohydrate contents were 2.74 to 4.8%.Key words: red tilapia, compensatory growth, quantity, quality