Zinc oxide nanoparticles are being synthesized through various methods. In study, spherical and crystalline particles were effectively synthesized by using alkaline precipitation method from zinc acetate dihydrate and sodium hydroxide. Mean size was lies around 36.77 nm and maximum particles were in 5 to 40 nm. The characteristics of synthesized ZnO NPs were determined by SEM EDX and XRD. In second part of study, consequence of ZnO NPs on the blood haematology, genotoxicity and DNA damage, oxidative stress and tissue alterations were studied by exposing Catla catla (55.7 ± 5.43 g weight and 25 ± 5 cm length) in chronic toxicity experiment (28 days). There were six treatments 0, 10, 20, 40, 60 and 80 mg L-1, where first treatment was the control and all treatments had three replications and each replicate had five fish. Blood and tissues samples were taken after the exposure of 7, 14 and 28 days of each treatment. The study revealed a significant difference of all the haematological parameters between control and experimental groups. The RBCs count was found increasing with the ZnO NPs concentrations and higher counts (2.91 ± 0.09 x106/mm3) were observed at 10 mg L-1; however, with the increase in dose intensity, a decrease in RBCs counts was seen due to anaemic conditions. The number of total WBCs counts was found to increase at 20 mg L-1 concentration (9329 ± 923/ mm3), which decreased after 40 mgL-1 to 80 mg L-1. Levels of haemoglobin, haematocrit, MCV along with the other parameters including the value of MCH and MCHC were also variant between ZnO NPs and control, The assessment of toxicity in term of genetic materials was detected by employing micronuclei along with comet assay. Result disclosed increase in number of comet and micronuclei with changing concentration of ZnO NPs. Elevated level of frequency in comets and micronuclei was documented after 28 days and 80 mgL-1 treatment. Oxidative anxiety was assessed by detecting levels of certain enzymes in fish body including the SOD, CAT, GST, MDA and GSH in 7, 14 and 28 days treatment of ZnO NPs. Gills and liver demonstrated a reduction in xiv activity of CAT and GST in a dose reliant style. However, SOD increased in activity in retort to ZnO NPs as in MDA. Gills and liver tissues also reflected histological alterations. It was revealed that cinnamon had higher amount of total phenolic (11.66 ± 1.76 mg GAE/100 g) and flavonoid content (11.55 ± 2.37mg RE/100 g), so; it is a good herb to decrease oxidative stress. FRAP, DPPH and ABTS free radicals having the values of 357.13 ± 50.90, 414.91 ± 97.63 and 917.22 ± 125.23 mg vitamin C equivalent per 100g respectively were used for confirmation. Both antioxidants (Cinnamon and Selenium) showed significant activities against oxidative stress. It was concluded; ZnO NPs persuaded toxicity and oxidative stress in treated C. catla where, cinnamon and Selenium have ameliorated effects reducing the oxidative stress and toxicity.