Masalah utama yang masih dihadapi dalam usaha budidaya ikan kerapu macan adalah tingkat mortalitas yang tinggi pada stadia larva. Perkembangan struktur sistem pencernaan dan fungsi enzimatik yang masih sederhana dan belum sempurna diyakini merupakan salah satu penyebab terjadinya hal tersebut. Penelitian ini bertujuan untuk (1) mendeteksi waktu awal aktivitas enzim pencernaan dan (2) mengetahui pola aktivitas enzim pencernaan pada larva umur 1 hingga 20 hari. Enzim yang dianalisis meliputi protease, amilase, dan lipase. Penelitian dilaksanakan dengan melakukan pengamatan secara berkesinambungan terhadap perkembangan yang terjadi secara alami pada larva selama periode waktu tertentu. Larva dipelihara di dalam hatcheri. Pakan yang diberikan kepada larva meliputi pakan alami rotifer Brachionus rotundiformis dan pakan buatan. Pengambilan sampel larva dilakukan pada larva umur 1, 2, 3, 5, 8, 11, 14, 17, dan 20 hari. Variabel yang diamati meliputi: aktivitas enzim, jumlah pakan alami pada saluran pencernaan larva dan histologis larva. Data hasil pengukuran dianalisis secara deskriptif kuantitatif dan ditampilkan dalam bentuk grafik. Hasil penelitian menunjukkan bahwa (1) aktivitas amilase dan lipase mulai terdeteksi pada larva umur 1 hari, sedangkan protease mulai terdeteksi pada larva umur 2 hari, (2) pada larva umur 1 hingga 20 hari, pola aktivitas protease dan amilase menunjukkan peningkatan dari larva umur 1 hingga 11 hari, dan kemudian cenderung menurun, sedangkan pola aktivitas lipase menunjukkan penurunan dari larva umur 1 hingga 8 hari, kemudian cenderung meningkat. Aktivitas protease dan amilase yang tertinggi selama periode waktu tersebut terjadi pada larva umur 11 hari, sedangkan aktivitas lipase yang tertinggi pada larva umur 17 hari

<p>Groupers were known as a high economically marine commodity and in order to support groupers production, the seed availability was the most important. Eggs are still as limited factor in hatchery production, for this reason the success of eggs transportation is one as base of successful production of seed. Planning on hatching time of eggs through different incubation temperature was an option to solve that problem. This experiment was aimed to find out the optimum temperature for groupers eggs and the minimum temperature to arrange incubation time and to plan the hatching time. Fertilized eggs were incubated into three beaker glasses of 1 liter in volume with the density of ± 250 eggs/liter. The incubation was done under laboratory condition at controlled temperature, i.e. (A) 21-22 ºC, (B) 24-25 ºC, (C) 27-28 ºC and (D) 30-31 ºC. The eggs that used were including orange spotted grouper (Epinephelus coiodes), brown marbled grouper (E. microdon), tiger grouper (E. fuscoguttatus) and humpback grouper (Cromileptes altivelis). Investigated variables were embryonic development pattern, incubation time and hatching rate. The result showed that the eggs incubated in temperature range of 24-31°C had the normal sequence of embryonic development pattern, but in temperature of 21-22°C performed irregular sequence and the embryonic development stopped at blastula or gastrula stage or even the eggs could still develop but the body of hatched larvae were abnormal. In lower temperature incubation, the incubation time was longer and the hatching rate of eggs was lower than those in higher temperature. Therefore the optimum temperature for incubation of orange spotted grouper, marbled grouper, tiger grouper and humpback grouper eggs ranged between 24-31 ºC, while the lowest possible temperature was 24 ºC.</p><p>Keywords: incubation temperature, embryonic development pattern, grouper eggs, hatching rate</p>

Blacksaddled coralgrouper Plectropoma laevis has been started to conserve to prevent from over exploitation. The study purposes were to determine the growth pattern during larvae to juvenile stage of Blacksaddled coralgrouper and their consumption rate to zooplankton rotifers Brachionus rotundiformis. Domesticated broodstocks have been rearing in 100,000 l concrete tanks. The eggs from spawning broodstocks were hatched and the larvae have been kept to juvenile. Larvae rearing was done in 6,000 l concrete tanks. During the rearing period, larvae were fed with zooplankton rotifer, artemia and artificial food. Parameters measured were eggs and oil globule diameter, larval total length, length of larval dorsal fin and ventral fin, the number of zooplankton that consumed by larvae and water temperature. Microscopic method was used to measure the parameters. The result showed that eggs and oil globule diameter ranged in 800-850 μm and 168-200 μm, respectively. Total length of newly hatched larvae was 2.53±0.13 mm. The growth pattern of total length from larva to juvenile stage was exponential, while the growth pattern of dorsal fin and ventral fin length was linear. Larvae grew very fast after 35 days old. The pattern of larval consumption rate to zooplankton rotifers was linear. Time period from larvae to juvenile stage was 45-55 days on water temperature 27-29oC.Keywords: growth, consumption rate, rotifers, larvae, Blacksaddled coralgrouper

Ikan kerapu sunu Plectropomus leopardus merupakan komoditas perikanan laut yang bernilai ekonomis tinggi, sehingga perlu dikembangkan dalam skala budidaya. Untuk meningkatkan keberhasilan pembenihan maka kualitas rotifer Brachionus rotundiformis sebagai pakan alami bagi larva perlu ditingkatkan. Uji coba penggunaan taurin sebagai salah satu bahan pengkaya rotifer perlu dilakukan, mengingat taurin merupakan asam amino bebas yang diharapkan dapat diabsorbsi dengan mudah dan cepat oleh larva. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan taurin terhadap pertumbuhan dan sintasan larva kerapu sunu. Penelitian dilakukan pada bak berkapasitas 6.000 liter. Selama pemeliharaan larva diberi fitoplankton Nannochloropsisocullata, rotifer, dan Artemia, serta pakan buatan. Perlakuan yang diujikan adalah: (A) penambahan taurin dan (B) tanpa penambahan taurin. Penambahan taurin dilakukan melalui proses bioenkapsulasi pada rotifer. Parameter yang diamati meliputi: panjang total, pertumbuhan duri sirip punggung dan perut, jumlah rotifer yang dikonsumsi oleh larva, serta sintasan benih. Hasil penelitian menunjukkan bahwa larva kerapu sunu umur 25 hari pada perlakuan A memiliki panjang total lebih besar (7,00±0,83 mm) dibandingkan pada perlakuan B (6,39±0,85 mm). Pertumbuhan duri sirip punggung dan perut larva pada perlakuan A terjadi lebih cepat dibandingkan pada perlakuan B. Jumlah rotifer yang dikonsumsi oleh larva pada perlakuan A lebih banyak dibandingkan pada perlakuan B. Secara statistik, semua parameter yang diamati tersebut berbedanyata pada kedua perlakuan (P<0,05). Sintasan benih kerapu sunu pada perlakuan A lebih tinggi (1,45%) dibandingkan pada perlakuan B (0,01%) (P<0,01). Dengan demikian maka penambahan taurin dapat meningkatkan pertumbuhan dan sintasan larva kerapu sunu.

The objective of this research was to know the effect of different feed on the growth of rotifer, Brachionus plicatilis population. Three combinations of feed namely (A) yeast + enrichment ingredient; (B) Isochrysis tahiti + yeast + enrichment ingredient and (C) Isochrysis tahiti were used as treatments in triplicates. Initial density of B. plicatilis was 100 ind./ml. Feeding frequency was twice per day, at 08:00 am and 16:00 pm. This experiment was carried out for 72 hours, and sampling was done every 24 hours. The results showed that the highest density for treatment A, B and C were 330.3±7.6, 305.0±63.8, and 300.0±10.0 ind./ml, respectively. In addition, the highest population reached at 660,667, 610,000 and 600,000 individuals for treatments A, B, and C, respectively. Percentages of B. plicatilis with eggs in each population were 15.14, 20.46, and 13.95% for treatments A, B, and C, respectively. These results indicated that yeast and enrichment ingredient gave the highest growth of Brachionus plicatilis population.