[Ambiphrya ameiuri (Ciliophora: Peritricha): its ultrastructure and distribution on the body of carp fry].

The mass infection of larvae and youngsters of carp fishes with the peritrichoid Ambiphrya ameiuri has been recorded in natural condition in the Rybinsk water reservoir. The uneven localisation of ambiphyrans on the body surface has been observed on the hosts Blicca bjorkna and Abramis brama. Most high density of parasites was on the breast, back and tail fins. The morphological variability of ambiphyrans in dependence upon their localisation on the fish body has been observed. Details being significant for the taxonomy have been studied by means of the scan electron microscope. It has been found that the scopulae (greatly developed attaching organ of A. ameiuri) in cases of heavy infection cover about 50-60% of the skin epithelium of fish larvae. In these cases the significant part of skin epithelium, which performs the respiratory function is excludes of the active oxygen supply that cause the illness and death of young fishes.