Indian Journal of Geo-Marine Sciences Vol. 43(12), December 2014, pp. 2327-2332 Prevalence and histopathology of branchioblastoma in Sardinella longiceps (Valenciennes 1847) of southeast coast of India K. Sinduja, R. Vijayakumar & A. Gopalakrishnan * Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai-608 502, Tamil Nadu, India * [E-mail: aquagopal@gmail.com ] Received 18 September 2013; revised 25 February 2014 Branchioblastoma in Sardinella longiceps is described in present study. Large tumour masses were found under the operculum. Tumour is characterized by the multilobed and pale to red in color and located in the brachial chamber of the fish. It varied in consistency from very soft and triable to hard and also vary in size from 17 mm to 33 mm in diameter and 18 to 44 mm in length. Prevalence study revealed that the higher incidence (0.046 %) of branchioblastoma was reported in Cuddalore in pre- monsoon 2011 and lower (0.010 %) in Parangipettai at summer 2010. Histopathologic examinations revealed that the chondroid tissue with basophilic nodules and the fibrovascular stroma were present in the tumour tissue. Presence of dark stained nucleus and also the granular cells were typical in the tumour tissue. This is the first report of branchioblastoma in Indian marine waters. [Key words: Branchioblastoma, Histology, Sardinella longiceps, Gill, Neoplasm] Introduction Indian oil sardine (Sardinella longiceps) has more economic value in all over the country. Oil sardines are rich in vitamins and minerals. Serving of sardines once a day can provide 13 percent of vitamin B2; roughly one-quarter of niacin and about 15 percent of vitamin B12 of the recommended daily value. Vitamins B help to support proper nervous system function and are used for energy metabolism, or converting food into energy. Oil sardines are enriched with major minerals such as phosphorus, calcium, potassium, and some trace minerals like iron and selenium. Oil sardines are also a natural source of omega-3 fatty acids, which promote healthy brain function and reduce the occurrence of cardiovascular disease 1 . The fish populations possess several kinds of real tumours, i-e pathological growth of tissue cells without previous inflammation, traceable infectious origin and mostly these tumours are benign and some of them are malignant in nature. Wild fishes found to have tumours in almost all organs, but most of them are of unknown etiology 2. Branchioblastoma is a neoplasm growing in the gill of fish. Neoplasms of the fish gills are very rare phenomena, and very limited papers were published on papillomas, squamous cell carcinomas, fibromas, chondromas, and branchioblastomas 3,4,5&6 . The branchioblastoma is prolific growth and it is incompatible with regular gill function and it is also lethal. Studies on gill changes, such as hyperplasia and lamellae distention have also been documented and these were due to physical and chemical agents and it was reported in salmonids, carp, bluegills, and white sucker 7,8,9&10 . Only one malignant gill tumour has been reported in an Amazonian fish (Cichlidae, Chaetobranchus semifasciatus) which was similar to metacercaria of trematodes 4 . Three spontaneous neoplasms have also been reported in rainbow trout 11&12 . Most of the studies with fish have been conducted with chemical induction of liver cancer. Further, experimentally induced neoplasm or hyperplasia in fish is primarily observed in the liver, kidney, spinal cord, testis, thyroid, intestine, and skin 13 discussed the use of aquatic models in cancer research. Teleosts gills are prone to different infection and lesions which may trigger further disease conditions. Common lesions of teleost gill are oedema, epithelial degeneration, necrosis, epithelial hypertrophy and hyperplasia which are due to the infectious diseases 7&14 . Hence the present study investigates the prevalence and pathology of the branchioblastoma in economically important S. longiceps. Materials and Method Sardine fish was examined quarterly basis since January 2008 to December 2011 from five different coastal regions of Tamilnadu, southeast coast of India (Fig. 1). Fishes were directly collected from fisherman and which was caught by gill net and purse seines. Fish caught in this way was examined for the presence of branchioblastoma by opening both the operculum. The tumour sizes were measured immediately after the examination. Tumour was dissected out for histological observations. Tissue were fixed in 10% neutral buffered formaldehyde solution for