Histopathological Studies on Nephropathy Caused by Oral Administration with Melamine and Cyanuric Acid in Fishes

Melamine and cyanuric acid have a triazine base and used to be supplemented in order to artificially inflate the apparent protein content in foods, resulting in occurrence of severe nephropathy in human infants and pet animals. These triazines are supplemented in fish food in China and the contaminated materials used to be treated to the fish diet in Japan. In the present study, we performed feeding examination with triazines at 200 ppm in the diet in tiger puffer (Takifugu rubripes), humpback grouper (Cromileptes altivelis) and koi (Cyprinus carpio). Tiger puffer and humpback grouper given melamine or cyanuric acid displayed the swollen kidney containing severe necrosis of renal tubules and glomerular damages. Experimental fishes given the both triazines displayed renal calculi consisted of melamine-cyanurate crystals within the renal tubules, followed by granuloma replacement. This study determined that oral administration of melamine and cyanuric acid caused severe nephropathy resembling cases of pet animals