Balantidium ctenopharyngodoni,an obligatory intestinal symbiont and possibly opportunistic parasite of grass carp（Ctenopharyngodon idella）,was first discovered and named by Chen（1955）.It mainly inhabits the cream-like luminal contents and spaces between mucosal folds of the hindgut.In the present study,twenty two or three-summer grass carp were bought from Wuhan Fruit-Lake Market in March 2009 and transported alive to the laboratory for further examination.All fish samples were dissected and the intestines were cut to collect the luminal co...
