A significant increase in the concentration of carbon dioxide in the atmosphere, as well as in the fresh water from the decomposition of organic and inorganic materials, is related to decreased pH values. The current study aimed to expose the blue tilapia fish, Oreochromis aureus, to different concentrations of acidity using ice carbon dioxide gas, as well as to examine the physiological, biochemical, and histological indicators of the fish. The findings presented an increase in the activity of the ALT and ALP enzymes in the fish exposed to acidic concentration (pH 6.5), while the measurements of the AST enzyme in the treated fish showed a decrease in the activity level. Histopathology examination of the tested fish exhibited a slight damage in fish gills within one hour of exposure, and it increased with increasing the time period.  An observable influence was noted in the secondary gill lamellae, represented by their bending and curling in numerous specimens. It was deduced that histopathological symptoms increased with prolonged exposure to the acid.