Nodular Gill Disease (NGD) is an infectious disease caused by various amoeba species and leads to major problems in Swiss trout farming. The disease is characterised by gill lesions and leads to respiratory problems, oxygen deficiency and mortality. Worldwide, it mainly affects freshwater salmonids in intensive aquaculture systems. In recent years, numerous outbreaks of gill disease in rainbow trout (Oncorhynchus mykiss) in Swiss aquaculture have led to mortality of up to 50 %. Freshwater amoebae are suspected to be the causative agent of NGD.
The gill score is a valuable initial diagnostic tool that helps fish farmers to identify and quantify gill diseases caused by amoebae. In recent years, NGS has been detected in more than 50% of larger rainbow trout farms. Six strains of amoebae have been found as part of an ongoing research project: Cochliopodium sp., Naegleria sp., Vannella sp., Ripella sp., Saccamoeba sp. and Mycamoeba sp. However, the significance of the different amoeba species for the development of NGD and especially for the development of gill lesions still needs to be investigated. Gill samples were taken from all affected trout for histological examination. In this master thesis, the histological samples will be examined and the changes will be assessed semiquantitatively.
Kontakt: Soyomi Seibold, Stefania Vannetti, Heike Schmidt-Posthaus
