author(s)
K Saravanan, J Praveenraj, T Sivaramakrishnan and R Kiruba Sankar

abstract
In the present study, a disease outbreak with 40% mortality in Catla catla and Labeo rohita was investigated at a carp seed farm located at South Andaman, India. Various symptoms like abnormal swimming, excessive mucus production, fin erosion and slight hemorrhage were observed in the affected fishes. Examination of moribund fishes revealed the causative agent as Argulus sp. The parasites were found attached to the skin and fins of all the examined fishes showing 100% prevalence. Heavy infestation of Argulus sp. was observed in C. catla and L. rohita with mean individuals of 90 to 130 parasites per fish. Molecular characterization of the obtained parasite using 28S rDNA (GenBank accession number MF926591) showed 94% sequence identity with Argulus japonicus and A. foliaceus, which further confirmed the causative agent. This is the first report on the outbreak of Argulus sp. from Andaman and Nicobar Islands, which also reveals the pandemic occurrence of Argulus sp. even in the freshwater aquatic system of these islands.