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Cold temperature shock tetraploidization of striped catfish Pangasianodon hypophthalmus (Sauvage, 1878) with different of temperature and age of zygote

Striped catfish (Pangasianodon hypophthalmus) has a relatively slow growth, so the operational cost of production is high and incomparable with the selling price, thus makes the cultivation of striped catfish is inefficient. Genetic quality improvement through polyploidization is to produce sterile triploid fish (3n) that can overcome this problem. The provision of triploid fish is more efficient through tetraploidization. Tetraploidization in striped catfish using cold shock treatment has never been done before. The purpose of this study was to determine the optimum tetra-ploidization condition using cold shock with temperature and different age of zygote in striped catfish. A completely randomized factorial design with two treatments i.e. three level of temperatures (8oC, 12°C, 16oC ) and two different ages of zygote (29 and 31 minutes after fertilisation-maf) and three replications was used. In addition, a control without applying temperature shock treatment was performed, Soaking process was conducted for 30 minutes. Tetraploid identification was done by calculating the maximum total of nucleoli per cell that was confirmed by calculating the total of chromosome. The results showed that the degree of hatching rate and abnormalities has a significantly different effect (P <0.05). Number of nucleoli per cell was 4 and chromosomes was 112 (4n=112) for tetraploid), whereas for diploid fish the maximum number of nucleoli per cell was 2 and the number of chromosomes was 56 (2n=56). The highest tetraploid percentage was obtained at a treatment  of  12oC at age of zygote 29 maf. Thus, the optimum condition of tetraploidization in striped catfish is using cold shock treatment of 12oC with the age of zygote of 29 maf.