The lernaea infested fingerlings of cyprinids showed the attachment of worm-like grey to greenish coloured copepods distributed along the both sides of the body, peduncle region especially at the base of caudal fin, base of dorsal fin and the buccal region. The sites of attachment were hemorrhagic nodules in C. carpio fingerlings and reddening without swollen margins in C. idella and H. molitrix fingerlings. The prevalence was 26.5, 32 and 33.1% among C. carpio, C. idella and H. molitrix fingerlings respectively and the highest infestation rate was in October and May. The lernaea infestation significantly decreased (4.3 up to 71.7%) the body weight of diseased fingerlings and this decrease was directly correlated with the infestation intensity. The histopathological alterations of the lernaea infestation were studied and Dipterex could not completely eliminate the lernaea from the infested C. carpio fingerlings