Toxicological effects of transition metal-doped titanium dioxide nanoparticles on goldfish (Carassius auratus) and common carp (Cyprinus carpio) Maghdad Pirsaheb a , Nammam Ali Azadi b , Maria Lucia Miglietta c , Mohammad Hossein Sayadi d , Jana Blahova e , Mokhtar Fathi f , Borhan Mansouri g, * a -Research Center for Environmental Determinants of Health (RCEDH), Kermanshah University of Medical Sciences, Kermanshah, Iran b Biostatistics Department, Faculty of Public Health, Iran University of Medical Sciences, Tehran, Iran c Enea CR Portici, P. le E. Fermi, 1, 80055 - Portici, NA, Italy d Department of Environmental Sciences, School of Natural Resources and Environment, University of Birjand, Birjand, Iran e Department of Animal Protection, Welfare and Behaviour, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences Brno, Palackeho tr.1946/1, 612 42, Brno, Czech Republic f Animal Sciences Department, Payam Noor University, Sanandaj, Iran g Medical Toxicology and Drug Abuse Research Center (MTDRC), Birjand University of Medical Sciences, Birjand, Iran highlights graphical abstract  Wavelengths increased in the order of TiO 2 < Cr/TiO 2 < Ni/TiO 2 < Fe/TiO 2 NPs.  Magnetic saturation degree of the metal-doped TiO 2 NPs were increased their toxicity.  Metal-doped TiO 2 NPs induced oxidative stress in both fish species. article info Article history: Received 6 September 2018 Received in revised form 15 October 2018 Accepted 16 October 2018 Available online 17 October 2018 Handling Editor: Tamara S. Galloway Keywords: Transition metal TiO 2 NPs Fish Antioxidant response Histopathological damages abstract The aim of present study was to assess the toxicological effects of transition metal-doped titanium di- oxide nanoparticles (TiO 2 NPs) on histopathological changes, behavioral patterns, and antioxidant re- sponses of goldfish (Carassius auratus) and common carp (Cyprinus carpio). The synthesized nanoparticles were confirmed by Transmission Electron Microscopy, Field Emission Scanning Electron Microscopy, X-ray diffraction, UVevisible, and Vibration Sample Magnetometer. Fish in four experi- mental groups exposed to sub-lethal concentrations of pure TiO 2 NPs (10 mg L 1 ), chromium (Cr), iron (Fe), and nickel (Ni) doped TiO 2 NPs for seven days. Statistical analysis of oxidative stress responses in gills showed significant differences in superoxide dismutase, total antioxidant capacity, and malon- dialdehyde parameters between two species and in all parameters than glutathione peroxidase between experimental groups and control group. In intestine, no significant difference was observed among groups, but oxidative responses were markedly different in all parameters among fish species. The histopathological analysis showed hyperplasia, fusion, and aneurism in the gills as well as degeneration, integration of villi, necrosis and erosion of the intestine. Our findings indicated that compare to pure TiO 2 NPs, exposure to transition metals-doped TiO 2 NPs induced oxidative stress and histopathological changes in both fish species. © 2018 Published by Elsevier Ltd. * Corresponding author. E-mail addresses: mpirsaheb@yahoo.com (M. Pirsaheb), azadi.n@iums.ac.ir (N.A. Azadi), mara.miglietta@enea.it (M.L. Miglietta), mh_sayadi@birjand.ac.ir (M.H. Sayadi), blahovaj@vfu.cz (J. Blahova), fathi_mokhtar@yahoo.com (M. Fathi), borhanmansouri@yahoo.com (B. Mansouri). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere https://doi.org/10.1016/j.chemosphere.2018.10.111 0045-6535/© 2018 Published by Elsevier Ltd. Chemosphere 215 (2019) 904e915