摘要：Dua percobaan telah dilakukan, yaitu tanpa dan dengan larva ikan. Percobaan pertama, yang menggunakan 3 konsentrasi diazinon 0. 2 dan 4 ppm dan 3 ulangan, mempelajari pertumbuhan rotifera, cladocera dan copepoda. Percobaan kedua mempunyai 2 perlakuan, yaitu diazinon 0 dan 4 ppm (yang terbaik dari percobaan pertama) serta 4 ulangan untuk mengevaluasi: 1) ketersediaan, pemanfaatan dan susunan jasad-jasad pakan, 2) pertumbuhan dan kelangsungan hidup larva, serta 3) perkembangan larva ikan. Larva yang berumur satu hari ditebar pada saat kelimpahan rotifera tertinggi di hapa dengan kepadatan 40 larva/1 atau 3.200 larva/hapa. Hapa (mesh 0,8 mm) yang berukuran 50x40x50 cm ditempatkan dalam kolam-kolam beton yang berukuran 4,25x2,00x 0,65 m. Kolam-kolam ini mula-mula dikeringkan selama 2 hari, dipupuk dengan kotoran ayam 1.000 g/m3 dan diisi air setinggi 50 cm. Keesokan harinya kolam dipupuk dengan urea dan tripel superfosfat masing-masing 20 dan 30 g/m3. Dua hari kemudian air diberi diazinon sesuai perlakuan. Hasil percobaan pertama menunjukkan bahwa diazinon meningkatkan ketersediaan rotifera. Populasi rotifera tertinggi dicapai di kolam yang mendapat diazinon 4 ppm. Percobaan kedua memberikan laju pertumbuhan harian dan kelangsungan hidup larva ikan serta ketersediaan dan pemanfaatan rotifer tertinggi pada pemberian diazinon 4 ppm. Kata kunci: Pakan alami, larva. Oxyeleotris marmorata, diazinon. kelangsungan hidup, pertumbuhan ABSTRACT Two experiments were conducted, without and with fish larvae. The first experiment, utilizing 3 concentrations of diazinon, i.e. 0, 2 and 4 ppm and 3 replications, evaluated the growth of rotifers, cladocerans and copepods. The second experiment had 2 treatments, i.e. 0 and 4 ppm diazinon and 4 replications evaluated: 1) the availability, utilization and composition of food organisms, 2) the growth and survival rates offish larvae, and 3) the development of larvae. One-day old larvae were stocked at times of highest rotifer concentrations in hapas at 40 larvae/1 or 3,200 larvae/hapa. Hapas (0,8 mm mesh) of 50x40x50 cm were placed in concrete ponds of 4.25x2.00x0,65 m. The ponds were dried for 2 days, fertilized with chicken manure 1.000 g/m3 and filled with water up to 50 cm deep. Next day, the ponds were fertilized with urea and triple superphosphate 20 and 30 g/m3 respectively. Two days later, the water was treated with diazinon according to treatments. The results of the first experiment showed that diazinon increased the availability of rotifers. The highest rotifer populations were obtained in ponds receiving 4 ppm diazinon. The second experiment gave highest daily growth and survival rates of fish larvae, te availability and utilization of rotifers at 4 ppm diazinon. Key words: Natural foods, larvae, Oxyeleotris marmorata, diazinon, survival, growth.
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