INTRODUCTION Only 30 years ago

Only 30 years ago, ?sh culturists and researchers complained of the lack of genetically improved ?sh and used this as a justi?cation for increased research in the area of genetic biotechnology (Maron & Park, 1994). Genetics plays a major and vital role in fisheries and aquaculture. Genetics is the study of heredity and the variation of inherited characteristics. (Dunham, 2004)defines aquaculture is an ancient form of fish farming. Aquaculture is the breeding of fish as well as the modification of fish. Genetics helps with evolution. Genetic manipulation also called as genetic engineering refers to the alteration of the genes of an organism and in aquaculture it is acknowledged for sex reversal in fish, for gene cloning breeding and chromosome manipulation. This review focuses on genetic manipulation in aquaculture. This review focuses on the advantages of genetics in fisheries and aquaculture including the issues regarding genetics.

Genetics was used to improve … although the use of genetics in fisheries and aquaculture was a success. Genetics is the method behind breeding. .Aquaculture has been and still is one of the fastest growing primary industry sector and it has managed to reduce pressure on wild fisheries.

Gene cloning
Genetics helps cloning which is the process of engineering fish
Gene cloning involves the change of the genetic make-up of an organism by either removing or adding chromosomes to get the desired organism. This experiment was done (Bardach, Ryther, & McLarney, 1972) on the tilapia fish that has been an important source of nutrition for man at least since noted history began and the arrival of modern conveyance it became even more valuable. Cloning was used to help in fisheries because the fish are at a risk of declining. The work of genetically engineered fish began 20 years ago and over that time about 35 species of fish has been genetically engineered in japan the
One big disadvantage of identical genes is that they will weaken our adaptations and power, which can make us subjected to certain diseases easily.
These fish are being engineered for traits that allegedly will make them better suited for industrial aquaculture and temperature tolerance. The genes engineered in these experimental fish come from a variety of organisms, including other fish, coral and bacteria,
With increased demand for aquacultured foods has come a need for more ef?cient production systems.
A series of breeding techniques were done in Vietnam in the late 1990’s. In Vietnam, traditional fish culture has been practiced as early as hundreds of years ago (Dan et al. 1997).

The use of hormones to change the sex of fish was first demonstrated in species of tilapia fish. Sex reversal also affects the gonads and not just the chromosomes. Sex reversal is much faster in males than in female fish species and unlike females, males grow during breeding periods (Bardach, Ryther, ; McLarney, 1972)

Chromosome manipulation
Chromosome manipulation research has a short history in fish compared to that of crops and animals. Since 1943, early attempts were initiated, and until recently various techniques have been developed to interfere with normal functioning of the metaphase spindle apparatus during nuclear cycles of cell division in fish eggs using several causal agents, both physical and chemical. As a result, individuals with differing genomic status, viz. polyploids (triploid and tetraploid), gynogenetics (both meiotic and mitotic gynogens) and androgenetics, are being produced in fish population. Among polyploids, triploid individuals are expected to be functionally and endocrinologically sterile due to their meiotic inhibition of gametogenesis and lack of essential steroid hormone levels to support gonadal growth. Such sterility in triploid fish can be of advantage to aquaculture where control of reproduction and population is desirable. The production of putative tetraploids might have tremendous impact, because of promising future of large scale production of genetically sterile fish (triploids) population lies with the mating of normal diploid and tetraploid individuals (Hussain, 1998)

Biotechnology is an important branch of animal breeding and genetics
There has been an explosion of research in this area, and now genetics and biotechnology are making a signi?cant impact on aquaculture and ?sheries, although potential for much greater progress exists. When improvements from biotechnology are considered, most people think of the impact on aquaculture and not the impact on ?sheries.
To enhance animal and plant production
Sustainable aquaculture has the potential to create employment

In conclusion, the use of molecular genetic techniques in fisheries research has increased dramatically over the past several years, largely due to the increased availability of techniques and an increased awareness of the value of genetic data (Park and Moran, 1994). Genetic techniques continue to grow. Although, sex reversal has a high diversity of advantages in fish farming the great disadvantages is that such hormone treated fish cannot be used for human consumption and due to government regulation on the use of chemical on food fish.