Silver Carp (Hypophthalmichthys molitrix) and Bighead Carp (Aristichthys nobilis) as Hosts of Sinergasilus Polycolpus, a New Copepod Species in the Ichthyoparasitofauna of Macedonia

Parasitic diseases represent negative factor, which in intensive fish farming can cause considerable damages in aquaculture. Parasites in the waters where they are present sometimes cause fish reduction, thereby directly affecting on fish stocks in the country. It is particularly important to recognize parasites and their vectors in fish in watercourses that supply water in fish breeding facilities, where beside parasitic infections, can lead to a significant reduction in fish production and even to mass fish deaths.The parasitological investigations were carried out from the period of autumn 2009 to summer 2012, by seasons, and a total of 47 specimens of silver carp ( Hypophthalmichthys molitrix ) and 53 specimens of bighead carp ( Aristichthys nobilis ) of different age groups obtained from two largest cyprinid fish farms near Bitola (Macedonia) were examined. Parasitic copepod Sinergasilus polycolpus was found on the gills in three - year old silver carp and bighead carp. The prevalence with Sinergasilus polycolpus in Hypophthalmichthys molitrix was 57,447 %, while the mean intensity was 10,148. The prevalence with Sinergasilus polycolpus in Aristichthys nobilis was 16,981 %, while the mean intensity was 20,000. Our findings of Sinergasilus polycolpus in silver carp ( Hypophthalmichthys molitrix ) and bighead carp ( Aristichthys nobilis ) are first recorded for Macedonia. At the same time, these two fish species represent new hosts for Sinergasilus polycolpus in Macedonia. Keywords: Hypophthalmichthys molitrix, Aristichthys nobilis, Sinergasilus polycolpus