A Leptomonas like parasite was found to be responsible for mortality of larvae
of Penaeus indicus and P. semisu2catus in the hatcheries. The mortality
occurred in protozoea and mysis stages but not in naupliar and postlarval
stages of prawn. The parasite exhibited polymorphism and three different
forms were observed. It occurred in the appendages, eyestalks, eyes and
rostrum of the host. Histological sections showed the presence of this parasite
in internal organs such as hepatopancreas, gut and abdominal muscle
