Seasonal variation in the occurrence of Pallisentis ophiocephali and Acanthosentis betwai (Acanthocephala) in relation to their fish hosts.

Male and female Channa striatus (BL.) and Labeo rohita (HAM.) were examined monthly for Pallisentis ophiocephali (THAPAR, 1930) and Acanthosentis betwai (TRIPATHI, 1959) infections for a period of two years. C. striatus showed greater proportion of infection with P. ophiocephali in March to May and males were significantly more infected than females. L. rohita showed greater infection with A. betwai in June and July and sexes were not differentially affected. The frequencies of male and female P. ophiocephali and A. betwai in the overall sample did not depart significantly from the expected ratio of 1:1 and 2:3 though in certain months the deviation from these ratios was significant.