Occurrence of parasitic isopods and copepods infecting the clupeidaen fishes of Malabar coast (India) was assessed in terms of prevalence, intensity, host/ site specificity and seasonal variation. 3 isopods (Joryma brachysoma, Anilocra leptosoma and Agarna malayi) and 4 copepods (Clavellisa hilsae, Peniculus fistula fistula, Pseudorbitacolax varunae and Naobranchia cygniformis) were recovered from the fishes, Escualosa thoracata, Tenualosa toli (hosts two parasites), Sardinella fimbriata and Anodontostoma chacunda (hosts three parasites) respectively. The prevalence and/or intensity of each recovered parasitic species showed statistically significant variation (P<0.05) according to seasons; the prevalence of isopod species was high during pre-monsoon and least in monsoon. Except P. varunae, which is more prevalent in pre- monsoon, all copepod species exhibited high prevalence during post- monsoon. The floor of branchial cavity forms the major site of infection for J. brachysoma and A. malayi recovered from E. thoracata and T. toli respectively. A. leptosoma prefers dorsal body surface, behind the head of T. toli for infection. P. fistula fistula, P. varunae and N. cygniformis prefer to infect respectively caudal fin, anterior and posterior mucus layer of inner operculum of A. chacunda indicating their microhabitat preference likely to avoid niche competition during the circumstance of triple parasitism. © 2019, Central Fisheries Research Inst. All rights reserved.