The most important infectious diseases of silver carp, Hypophthalmichthys molitrix, and their control and prevention

Sever mortalities of Silver carp, Hypophthalmichthys molitrix, with various clinical symptoms including Lethargy, subcutaneous hemorrhages on operculum, fish sides, base of fins, mild exophthalmia and ascites in the abdominal cavity (yellowish, reddish or Clear), extensive or focal hemorrhages on the Viscera and yellow or colorless skin and mortalities in some cases has caused huge economic losses. In some studies, bacterial agents have been reported as causal agents of mortalities but other researchers have identified clinical and necropsy symptoms as suspected to viral diseases. Since the poor conditions can lead to fish mortality following infections, timely detection of infectious agents and the use of preventive and controlling methods for these diseases, along with improved pond management, can prevent the occurrence of diseases and the spread of diseases. Various studies have shown that the most common infectious agents in fish are bacterial agents such as aeromonas, especially aeromonas hydrophila, and two species of P. aeruginosa and P. fluorescens. Other bacterial diseases caused by Proteus rettgeri and Staphylococcus aureus have also been reported as pathogens in this fish species. On the other hand, silver carp is susceptible to viral diseases including spring viremia of carp. With the presence of a weakened immune system due to a poor water and nutrition management, fungal agents can also affect the fish that are not usually the primary cause of mortality. At the same time, prompt diagnosis of pathogens and the implementation of appropriate health management through the use of bio-security methods can prevent further damage