Haemoflagellates of the genus Trypanosoma Gruby, 1843 are prevalent in fresh water fishes and are transmitted by leech. A total of 133 Clairus batrachus were examined for haemoflagelates. The fishes were collected from ponds and water bodies of Purba Medinipur district, West Bengal, India, from January, 2006 to July, 2007. The slides were prepared taking blood from both males (97) and females (36). It was found that only 19 out of 36 (52.78%) females and 31 out of 97 (31.95%) males were infected. Thus females were recorded with a higher prevalence of trypanosome infection than males. There was a significant difference (P<0.05) in the infection rate with trypanosomes in males and females.