Posthodiplostomatosis in a fishpond in Serbia

Posthodiplostomatosis (black spot disease) is a disease of young freshwater fish species of families Cyprinidae and Cobitidae, resulting from infection with metacercaria, which is the penultimate developmental stage of Posthodiplostomum cuticola. Metacercaria give rise to black cysts located primarily in the skin, muscles and on the fins. The disease caused by P. cuticola in certain fish species is first detected in a fishpond in Serbia, as presented in the current work, whilst in natural waters it has been existing for many years. Diagnosis of the infection in the grass carp (Ctenopharyngodon idella) and the bighead carp (Aristichthys nobilis) was based on the occurrence of dark discolorations and cysts of the parasite on the fins. Cysts measured approximately 1 mm in diameter, were confirmed by histopathological means. Posthodiplostomatosis occurred in fishponds in which preventive measures were not implemented, i.e. where the nurseries were not dried up and mechanically cleaned.