Turk. J. Fish.& Aquat. Sci. 23(8), TRJFAS18762 https://doi.org/10.4194/TRJFAS18762 Published by Central Fisheries Research Institute (SUMAE) Trabzon, Türkiye R E S E A R C H P A P E R Evaluation of Toxicity Induced by Engineered CuO Nanoparticles in Freshwater Fish, Labeo rohita Sana Aziz 1, * , Sajid Abdullah 1 1 University of Agriculture, Faisalabad, Faculty of Sciences, Zoology, Wildlife and Fisheries, Faisalabad, Pakistan Article History Received 25 December 2020 Accepted 27 March 2023 First Online 02 February 2023 Corresponding Author Tel.: +03167465714 E-mail: sana.aziz1994@gmail.com Keywords Labeo rohita Toxicity Accumulation Oxidative stress Genotoxicity Abstract With the fast development of industries relevant to nanotechnology, the inappropriate disposal of nanoproducts may initiate a new source of pollution in aquatic ecosystems, thus posing a possible danger to aquatic life. This study evaluated the eco-toxicological effects of waterborne copper oxide nanoparticles (CuO-NPs) having a 32.84nm size and rod shape on a freshwater fish, Labeo rohita. 96-h LC50 of CuO-NPs was 353.98mg/L. Two sub-lethal concentrations equivalent to 1/3rd and 1/5th LC50/96h (70.79 and 117.99 mg/L) of CuO-NPs were selected for 15, 30, and 45-day exposure tests. Bioaccumulation for the 1/3rd 96h LC50 was significantly higher compared to 1/5th of 96-h LC50 of CuO-NPs. There was a sharp decrease in the CAT activity and this decline ultimately increased the TBARS contents. The highest percentage of damaged nuclei and genetic damage index in fish erythrocytes was recorded at the highest concentration and after 45 days of treatment. The adverse effects of CuO-NPs were examined to be dose and duration dependent with increasing extent during all studied time intervals. Summarizing, exposure to sublethal concentrations of CuO-NPs is sufficient to cause alterations in ecotoxicological endpoints such as metal overload, oxidative stress and genotoxicity after chronic exposure Introduction With the rapid development of nanotechnology, metal oxide nanomaterials have received great attention because of their typical physicochemical properties, primarily attributed to their higher surface area compared to their bulk materials. Moreover, factors regarding size, shape, chemical properties, dissolution, and aggregation are specifically advised to be the most crucial parameters that influence the attributes of nanoparticles (Nel et al., 2006). Copper oxide nanoparticles (CuO-NPs) commonly synthesized nano-materials due to their good catalytic, antibacterial, and thermo-physical attributes (Prasad et al., 2016), are commonly utilized in chemical processes, cells, sensors, electronics, nutrient protection, textile industries, coatings, drug delivery, water management, and agriculture (Keller et al., 2017). Aquatic ecosystems are the eventual destinations of pollutants (Yalsuyi & Vajargah, 2017). Inevitably, increased production and use of CuO-NPs results in bio-accumulation in aquatic biota and ultimately entered in higher trophic levels (Zhao et al., 2011; Shaw & Handy, 2011), posing a possible danger to non-target living things. For Cu NPs, the PEC (predicted environmental concentration) in some waters were about 60 µg/L (Chio et al., 2012). The toxicity of copper ions to aquatic life is well noted and as a redox metal, Cu takes part in Fenton and Haber–Weiss reactions, causing the reactive oxygen species (ROS) formation and oxidative stress (OXS) (Bebianno et al., 2004). All aquatic animals have improved systems to defend against damage induced by reactive oxygen How to Cite Aziz, S., Abdullah, S. (2023). Evaluation of Toxicity Induced by Engineered CuO Nanoparticles in Freshwater Fish, Labeo rohita. Turkish Journal of Fisheries and Aquatic Sciences, 23(8), TRJFAS18762. https://doi.org/10.4194/TRJFAS18762