Cross-infection experiments confirm the host specificity of Goussia spp. (Eimeriidae: Apicomplexa) parasitizing cyprinid fish

Abstract

Summary. The host specificity of the coccidian Goussia carpelli (Leger et Stankovitch, 1921) (Eimeriidae: Apicomplexa) was studied in aquarium experiments. Oocysts were obtained from the gut of 1- to 2-year-old common carp intensively infected with Goussia carpelli. These oocysts were mixed into mud containing infection-free oligochaetes ( Tubifex tubifex and Limnodrilus hoffmeisteri). Laboratory-cultured fish demonstrated to be infection free were infected by feeding oligochaetes. The susceptibility of 3-5 cm long fingerlings of 8 fish species [common carp (Cyprinus carpio), goldfish (Carassius auratus), barbel (Barbus barbus), bleak (Alburnus alburnus), roach (Rutilus rutilus), bream (Abramis brama), white bream (Blicca bjoerkna) and vimba (Vimba vimba)] was experimentally evaluated. In the gut of common carp, intensive infection developed each of eight experiments, and oocysts were consistently detectable in the faeces and gut s crapings on days 11-20 after feeding the fish with the oligochaetes. At the same time, oocyst formation could not be demonstrated in the gu t of the other seven cyprinids. In another experiment of similar design, only the goldfish could be infected with oocysts obtained from naturally infected goldfish, and no infection was established in the common carp. The results of these experiments suggest that G. carpelli is strictly specific to common carp, while Carassius species most closely related to the common carp are parasitised by a distinct species of Goussia with which it shares morphological similarity .