Pollutants lead to undesirable changes in aquatic physiology. One of these changes is the expression of cytochrome P450 enzymes (CYPs) that are found in various organisms, including aquatic organisms. CYPs are too diverse and metabolize many substrates, but their structure is highly protected. CYP1 is one of the first enzymes produced in the first phase of the response to contaminants in the detoxification of extracellular compounds such as toxins, heavy metals, carcinogenic chemicals, drugs and petroleum contaminants. This enzyme is also expressed in stress-free conditions, but its expression changes in the presence of contaminants and stressors, which is affected by the aquatic species, age, sex, type of contaminant, concentration and duration of exposure to the contaminant and these changes can be used as biomarkers of pollution in aquaculture. Increasing its level can increase the resistance, growth and survival of aquatic animals against environmental pollutants. In this study, we investigate the role, importance and function of cytochrome p450 oxidase in fish.