Polyparasitism by monogenea in wild Hemichromis elongatus (Guichenot, 1861) (Pisces: Cichlidae): A study model encouraging the prevention of heavy parasitic infections in fish farms

Abstract

The present paper aims to study the occurrence of monogenean species infecting the gills of wild Hemichromis elongatus (Pisces). Fish specimens were caught with nets, fixed in 10% formalin and then dissected. Monogenean specimens found were removed under a stereomicroscope with a needle, and then mounted between slide and cover slip in a drop of hematoxylin eosin. Among the five parasite species found, only O. voltaensis and C. euzeti were found infesting their host alone. There were significant differences between mono-parasitism and polyparasitism both in parasite load and infection rate, which were higher in simultaneous infestations. These monogenean ectoparasites best exploit their common host when they co-occur. This phenomenon observed in natural conditions is a threat in fish farming where high host densities favor parasite transmission. We therefore recommend quarantining native fish specimens captured in the wild, periodic pond sanitization and deworming.