Red Sea bream Iridovirus (RSIV) was detected in Asian Sea Bass (Koddai fish grown in cages by fish farmers in Udupi) by a team of experts from the Fisheries College in Mangaluru. RSIV, which was earlier unknown in Indian waters was for the first time identified and isolated in the country.

Fisheries College Dean Dr Senthil Vel said in the year 2018-19, the fish farmers in the Udupi region brought up the issue of death of Asian Sea bass (Lates Calcarifer) grown in the cages to the notice of the Fisheries College.

The diseased fishes exhibited abnormal behaviour and clinical signs including slow-motion, lethargy, reduced feeding, erratic movement along the sides of the cages.

A team of pathologists including Dr Girisha S K, Puneeth T G, Nithin M S, Dr Naveen Kumar B T, Dr Ajay S K, Dr Vinay T N, Dr Suresh T, Dr Venugopal M N and Dr Ramesh K S from the department of Aquatic Animal Health Management (AAHM), College of Fisheries, Mangaluru analysed samples.

‘Standard procedure’

The dean said that standard procedure was followed to identify the cause of such behaviour in the fish and found that the Asian Sea Bass were infected by the Red Sea bream Iridovirus (RSIV), he added.

AAHM in the College of Fisheries, Mangaluru, has been carrying out disease surveillance programmes under the “National Surveillance of Aquatic Animal Disease”

project in both freshwater and brackish water cultured fishes.

The programme was initiated by the National Bureau of Fish Genetic Resources (NBFGR), Lucknow.

The prime objective of the project is to create awareness about emerging aquatic animal diseases and preventive measures among the fish farmers in the regions where fish culture and shrimp farming are being carried out.

RSIV was first detected in Japanese cultured Red Sea Bream farm in 1990s. More than 30 marine and brackish water fish species such as Sea bass, Grouper fish and Red sea bream etc, are known to be susceptible to this virus.

This virus can cause mortality up to 100% depending on host fish species, size, age, water temperature and other culture conditions.

Since RSIV is a new emerging virus in Indian waters, proper management measures have to be undertaken to mitigate its spread, said Dr Senthil Vel.

He said further studies are being carried out in the college and the process of preparing preventive measures for mitigation of the virus is in the progress.

However, proper scientific management practices can be adopted to control and prevent the spread of RSIV such as stocking pathogen-free fish, implementing hygiene practices on farms, avoiding practices that can decrease water quality such as overcrowding and overfeeding. Fish farmers can contact: 0842-2246384 for help from College experts.