Immunostimulants and Fish Culture: An Overview

Aquaculture is one of the fast growing foods producing sector worldwide. Cultured marine, freshwater fish as well as shellfish species are major contributors to fish production and also increase the annual production. Fish farming constitutes unique and significant berth in industrial scale production worldwide. Due to intensive fish farming practices, infectious disease pose a major problem in aquaculture industry globally especially causing heavy loss to farmers. Fish disease is rarely a simple association between pathogen, a host fish and environmental problems, such as poor water quality or others stressors often contribute to the outbreak of disease. Various types of antibiotics, chemotherapeutic and vaccines are in use to control or prevent viral, bacterial, parasitic and fungal diseases. Unfortunately, vaccines are usually not able to confer protection on their own; especially those vaccines based on recombinant antigens or inactivated pathogens. Therefore, an alternative inexpensive and effective substitute is needed to enhance the activity of drugs. In this vista, use of adjuvants or immunostimulants is good remedy to increase the vaccine efficacy to control fish and shrimp diseases. Immunostimulants (IS) is a naturally occurring compound that modulates the pathogens via facilitate the function of phagocytic cells and also stimulate the natural killer cells (NK), complement, lysozyme and antibody responses of fish. The activation of the immunological functions by IS is associated with increased protection against both infectious and non-infectious diseases. In this review, we summarized the therapeutics importance of immunostimulants in fish culture and control of diseases development and progression.