Survey of Saprolegnia sp. in cage cultured carp in Tikves Lake in 2005 and 2006

Fish cage culture is one of the most intensive and productive aquaculture methods. Besides all production advantages, this system is facing with health problems in cultured fish due to lack of prophylactic measures and increased disease susceptibility as a result of the culture technology. In order to determine the presence of the Saprolegniosis in the warm water cage culture systems, a two year monitoring was conducted. The survey included investigation in 12 carp (Cyprinus carpio) cage culture systems in Tikves Lake in the period 2005 and 2006. The objects of examination were only the growing categories of carp (yearlings). From each farm 30 specimens were examined. The survey included clinical and pathological examination as well as routine laboratory diagnostics – microscopic examination and isolation of the agent on fungal specific nutrient agar. The conducted research, demonstrated 91,66% prevalence of the causitive agent in the investigated farms in 2005 and the prevalence of 33,33% in 2006. Although the disease was present in 2005 and 2006, obtained results demonstrated deviation in the appearance and presence of Saprolegnia sp. in the investigated period. The determined difference was a consequence of the applied ichtyotechnical and ichtyosanitary prophylactic measures, resulting with significantly lower prevalence in 2006.