If the urine smells fishy, then the possible causes: First, urine concentration or long periods of time without urination, then there will be urine in the bladder for volatilization, some of the esters emit abnormal odor, can be manifested as a heavy fishy smell, usually not accompanied by urinary frequency, urinary urgency and other urinary tract irritation symptoms, and can show a deepening of urine color, such as brownish yellow or brown, etc. Second, if there are urinary tract infections, such as urethritis, cystitis, pyelonephritis, etc., the presence of bacteria decomposing the proteins in the urine can produce a more unpleasant odor. It may also contain cellular metabolites, bacteria or the presence of pus, which can aggravate the odor of urine. Mostly accompanied by urethral irritation symptoms, there will be frequent urination, urinary urgency, painful urination, etc. It is recommended to carry out routine urine examination and urine culture examination to confirm the diagnosis of the presence of infection. Thirdly, if there is sugar, protein or mixed with bilirubin and urobilinogen in the urine, it may cause abnormal odor of urine, it is recommended to conduct routine urine examination to further identify.