Fish Breeding and Biotechnology

In this review four different methods which have been used for cultivating new breeds of fish of agricultural importance are discussed. They are; 1. Natural and artificial selection, 2. Artificial sexual hybridization, 3. Nuclear transplantation and 4. Gene transfer. Among them, natural and artificial selections and sexual hybridization are traditional, sexual and non-biotechnical methods. They are popularly and successfully used in fish farming practice in the history. But their further application is limited because of the difficulties of composition of sexual combinations between distantly related species. Furthermore identification and composition of the characteristics which are to appear in the hybrid fish presents many problems. Nuclear transplantation and gene transfer are two newly developed methods for attempting to cultivate new breeds of fish. Biotechnology thus offers the chance of transferring genetic materials or molecules between different fish species. It is expected that these two methods will ultimately replace the sexual methods for obtaining more stable, predictable hybrid fishes. Because no species-specific limitation will appear in those genetic transfer combinations and the target genes which were the newly developed fish in unique ways. Some important approaches have already been made in those research areas, but some special problems, theoretically or technically, have to be solved before those biotechnical methods can successfully be applied to fish culture on commercial scales.