This study aimed to compare histopathological effect of waterborne silver nanoparticles and silver salt (AgNO 3 ) on the gills and liver of Carassius auratus. Therefore, one hundred and five live specimens of goldfish were obtained and treated in five aquariums with 0, 0.01, 0.025, 0.05, and 0.1 ppm of AgNO 3 and 0, 0.1, 0.5, 1, and 5 ppm of Ag nanoparticles (mean particle size of 5 nm). Fish were sampled after 14 days of exposure. Results showed that the kinds of pathologies observed with Ag NPs were broadly of the same type as AgNO 3 including hyperplasia, edema and lifting of the gill epithelium, and lamellar fusion of the gills, and hemosiderosis, hemorrhage, hydropic swelling, and pyknotic nuclei of the liver. Overall, the data showed that although Ag nanoparticles and AgNO 3 pathology were similar, but Ag nanoparticles caused less injury than AgNO 3 in the gills and liver of goldfish. Therefore, it is more proper to use nanoform of Ag in industrials.