First report of monogenean flatworms from Lake Tana, Ethiopia: gill parasites of the commercially important Clarias gariepinus (Teleostei: Clariidae) and Oreochromis niloticus tana (Teleostei: Cichlidae).

Moges Beletew,Maarten P M Vanhove,Abebe Getahun

doi:10.1186/s13071-016-1691-2

Abstract

BackgroundLake Tana is the largest lake in Ethiopia and the source of the Blue Nile. The lake harbours unique endemic cyprinid fish species, as well as the commercially important endemic Nile tilapia subspecies Oreochromis niloticus tana and the North African catfish Clarias gariepinus. Its endemicity, especially within the Labeobarbus radiation, its conservation importance and its economic indispensability attract scientific interest to the lake’s ichthyofauna. Fish parasites of Lake Tana, however, are hitherto poorly known, and no formal report exists on its monogenean flatworms. For sustainable aquaculture and fisheries development, it is essential to study monogenean fish parasites in these economically most important fish species. Moreover, it remains to be verified whether this unique ecosystem and its endemicity gave rise to a distinct parasite fauna as well.ResultsNile tilapia and North African catfish hosts were collected from Lake Tana in 2013. Nine species of monogenean parasites of two orders, Gyrodactylidea Bychowsky, 1937 and Dactylogyridea Bychowsky, 1937, were recovered. Gyrodactylus gelnari Přikrylová, Blažek & Vanhove, 2012, Macrogyrodactylus clarii Gussev, 1961, Quadriacanthus aegypticus El-Naggar & Serag, 1986 and two undescribed Quadriacanthus species were recovered from C. gariepinus. Oreochromis niloticus tana hosted Cichlidogyrus cirratus Paperna, 1964, C. halli (Price & Kirk, 1967), C. thurstonae Ergens, 1981 and Scutogyrus longicornis (Paperna & Thurston, 1969).ConclusionsExcept for M. clarii, all species represent new records for Ethiopia. This first study on the monogenean fauna of Lake Tana revealed that the lake’s North African catfish, as well as its endemic Nile tilapia subspecies, harbour parasites that are known from these host species elsewhere in Africa.

Highlights

Lake Tana is the largest lake in Ethiopia and the source of the Blue Nile
All five inspected Nile tilapia specimens were infected by 13–32 monogeneans, with a mean intensity of 19.3 monogeneans/fish
Specimens belonging to Gyrodactylus, Macrogyrodactylus and Quadriacanthus, totaling five species, were recovered from Clarias gariepinus

Summary

Introduction

Lake Tana is the largest lake in Ethiopia and the source of the Blue Nile. The lake harbours unique endemic cyprinid fish species, as well as the commercially important endemic Nile tilapia subspecies Oreochromis niloticus tana and the North African catfish Clarias gariepinus. For sustainable aquaculture and fisheries development, it is essential to study monogenean fish parasites in these economically most important fish species. It remains to be verified whether this unique ecosystem and its endemicity gave rise to a distinct parasite fauna as well. Lake Tana is the largest lake in Ethiopia with a surface area of 3050 km and a maximum width and length of 68 and 78 km, respectively It contains half the country’s freshwater resources and is the third largest lake in the Nile Basin. These rivers supply more than 95 % of the total annual inflow to the lake (see [1] and references therein) (Fig. 1)

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