Health status and microbial quality of common carp reared in a pond fed with treated wastewater from a slaughterhouse

Wastewater from slaughterhouses in many countries is still discharged into rivers, without having been adequately treated. Such wastewater contains plenty of organic matter which is an ideal source of nutrients for fish, but also for the development of microorganisms. Thus, usage of wastewater in aquaculture could become a health risk for humans, fish due to the introduction of microorganisms into the aquatic environment. In the available literature, there is insufficient data on health and meat safety regarding common carp reared in purified wastewater. The aim of this study was to assess the health and meat safety of common carp cultivated in a fishpond supplemented with slaughterhouse wastewater that was subjected to tertiary treatment. The number of parasites was not significant and not a single parasitic disease was found in this study, but the number of parasite species detected was as expected and typical for carp production. No spring viraemia of carp or koi herpesvirus disease was found. The carp cultivated were in good health and completely safe for human consumption in terms of the presence of microbial contaminants. The safe use of wastewater for fish rearing should be encouraged, but proper treatment of wastewater must be applied before its use.