Ananda Raja, RTANUVASSridhar, RBalachandran, CPalanisammi, ARamesh, S2019-07-022019-07-022016http://krishikosh.egranth.ac.in/handle/1/5810111318TNV_TH_2016_DPV13023Active surveillance conducted in 37 Litopenaeus vannamei farms in Kancheepuram and Thiruvallur districts, Tamil Nadu during August 2014 to February 2015 showed disease outbreaks in 40.6 and 13,5 per cent of the farms, respectively. There was 48.6 per cent vibriosis outbreaks with 20 to 100 per cent mortality between 20 and 80 days of culture (DOC) in shrimp farms infected with V. parahaemolyricus (VP). No vibriosis was observed in farms maintained by the young farmers of 26-35 years, freshwater ponds and the ponds aged less than 5 years. Vibriosis outbreaks were more among the non-graduate maintained farms (43.2%), the ponds sized less than l ha (43.2%), the farms without reservoirs (43.2%), ponds within 4 km from the sea and within 300 meters from the creek (48.6%), farms having same inlet and outlet for water intake and drainage (46%), stocking density more than 30 PLs per m2 (43.2%), unorganized and unapproved farms (43.2%), water drained without chlorination (45.9%), the Zero water exchange system (32.4%), storing feed more than 10 days at farm site (45.9%), farmers doing feeding regulations on their own (43.2%), and no bio-security (48.6%). Vibriosis led to a net loss of Rs. 478,377/- per ha from diseased ponds.enVeterinary ScienceThesis