Pathological effects of repeated doses of malachite green: a preliminary study

This study reports the histopathogical observations made upon the livers and gills of rainbow trout exposed to a continuing series of exposures to l·6ppm 40 min baths of malachite green at weekly intervals. After the third week of exposure, sinusoidal congestion and focal necroses were evident on the livers. At the ultrastructural level, consistent mito‐chondrial damage was evident with swelling and disruption of the cristac, together with dilation of the rough endoplasmic reticulum. Nuclear alterations increased in severity in the later periods of exposure. However, these hepatic changes were not severe enough to be reflected in scrum protein changes. In the gills of treated fish, separation of the epithelial lining from both lamellar and interlamellar regions was noted and lamellar cell necrosis and leucocyte infiltration became more frequent with increased exposure.