Posthodiplostomatosis in a fishpond in Serbia

Abstract

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.

Postodiplostomatoza je oboljenje mlađih kategorija slatkovodnih riba izazvano infekcijom metecerkarijama trematode Posthodiplostomum cuticola. Promene se zapažaju u vidu crnih cista lokalizovanih prvenstveno u koži, subepidermalnom tkivu i na perajima. Najčešće se javlja kod vrsta riba familija Cyprinidae i Cobitidae. Iako je infekcija duži niz godina prisutna u otvorenim vodama, u radu je opisan prvi nalaz infekcije kod riba iz ribnjaka u Srbiji. Postodiplostomatoza je dijagnostikovana kod belog amura (Ctenopharyngodon idella) i sivog tolstolobika (Aristichthys nobilis). Promene su bile karakteristične, makroskopski vidljive kao tamnosiva do crna kružna polja diskoloracije najčešće na perajima. Njihova prosečna veličina iznosila je 946.5±25.19 μm kod belog amura i 944.5±23.50 μm kod tolstolobika.