Development of the maturation- and ovulation-induction method in cultured tiger puffer Takifugu rubripes by hormonal treatments

We developed an effective method for the induction of oocyte maturation and ovulation in the cultured tiger puffer Takifugu rubripes by hormonal treatments, in order to supply the fertilized eggs for seedling production. Ovarian biopsy just prior to the hormonal treatments revealed the oocyte diameter and developmental stages of the oocytes. A luteinizing hormone-releasing hormone analogue (LHRH-a) cholesterol pellet (400 mu g/kg) implantation successfully induced oocyte maturation for three-year-old cultured tiger puffer which had yolk accumulated ovaries. Thereafter, single injection of HCG (500 IU/kg) combined with chum salmon pituitary (SP) homogenate (7 mg/kg) was applied to the fish to synchronize ovulation among fish. Ovulation mainly occurred between 96 and 120 hours after HCG+SP injection. Thus, a technique for obtaining eggs of high quality from the cultured tiger puffer was developed.