Observation of parasitic behaviour of an invasive neozootic fish species, the topmouth gudgeon, Pseudorasbora parva (Actinopterygii: Cypriniformes: Cyprinidae), on other cyprinid fishes

The objective of this study was to observe and document behavioural factors of parasitism of an invasive neozootic fish species—the topmouth gudgeon, Pseudorasbora parva (Temminck et Schlegel, 1846)— on different cohorts of 1-year-old and 2-year-old common carp, Cyprinus carpio Linnaeus, 1758, as well as 3-year-old tench, Tinca tinca (Linnaeus, 1758), after the overwintering period in ponds and subsequently in aquaria. Fishes cohabited the ponds for seven months and the aquaria for one month. After this period carp and tench were examined for visible lesions on the body surface. During the cohabitation period cyprinids were actively nibbled by the neozootic fish species P. parva. Such attacking or nibbling caused injuries on the skin and deep lesions, which can be interpreted as predation or even parasitism.