Abstract

The use of hipophysis in the spawn induction of fish that sex maturated in captivity started in Brazil more than 50 years ago. This technique has been highly modified, and in the actual time there are using many chemicals such as Chlomifen, Perisol Sereno, etc. This research had been conducted using five females and ten males of Lurjanus griseus, selected from 2 00 spawners that reach sexual maturity from June to August every year and have been cultured in 400 m3 pond. Six groups of fish, two for treatment, each with one female and two males, were maintained in 800 l tanks with filtered seawater and air continuously. Two groups were treated with LH-RH, 30 ng/kg to female fish and 15 ng/kg. to male fish. Two groups were treated with HCG, 2 IU/g to female fish and l IU/g to male fish. As a control two groups were treated with physiological sera, 0.5 ml for female and 0.25 ml for male. After 24 hours the water was renewed. The temperature was 28 +- 2 °C and the salinity 38%. The fish groups treated with LH-RH spawned at 38 and 46 hours respectively after injection. The fertilization rates were 96 and 98%, and thethe hatch out rates were 78 and 90%, at 24 and 36 hours. respectively. The larvae average size was 2856.34 _+ 137.10 pm. Fifteen percent of these larvae had malformations and died before 36 hours after hatching. The fish treated with HCG spawned at 52 and 70 hours respectively after injection. The fertilization rate were 65 and 90%, with 80 and 94% hatching rate. A 5% of the larvae had malformation and died. In the groups treated with physiological sera it was not detected spawn. First feeding occurred 36 hours after hatch out. The larvae were reared on a mixture of rotifer Brachionus plicatilis and the copepodite of Oithona ovalis (8: 6/ml). The larvae from HCG treatment diet at day 25. while the larvae from LH-RH groups reached juvenile stage, from then they have been feeding with wild zooplankton and bait fish. After 120 days from hatching the average weight was 14.8 g.

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