Study of pathological effects of an organic germicide bathing on rainbow trout

The aim of this study was evaluation an organic germicide (Aquagerm) histological affects on Rainbow trout (Oncorhynchus mykiss) vital tissues. This new disinfectant is an aquatic antiseptic and mixed-oxidant disinfectant which is produced for the first time in Iran. This new product mechanism is based on oxidant properties of pro-sulphate which attack crucial structures of pathogens. In this study, forty healthy fish were selected and divided in to two groups as control and treatment. The treatment group was treated with 1/2000 concentration of organic germicide for 45 min (according to the manufacturing protocols). At 4, 8, 12, 24, 48 and 96 h after bath challenge, 5 specimens were collected from treatment and one from control group. Gill, brain, kidney, and liver of all fish were sampled. Some histological damages such as edema and detachment of basic layer in secondary gill filaments were observed in gill microscopy results. The most important histological changes observed in the brain were congestion of some blood vessels. Furthermore, some evidences of increased melano-macrophage, glomerular shrinkage, and dilatation in Bowman capsules were recorded whereas no any damages were observed in liver. All histological changes removed after 48-96 h. It could be concluded that, all pathological observations in this study were just a natural response of fish body after exposing to the new disinfectant, and they were not recorded any damages like those which happen against hazardous chemicals. It seems that there is no risk associated with the consumption of this disinfectant for the fish tissues.