If the urine smells fishy, the possible causes are as follows: 1. urinary tract infection, the presence of more bacterial metabolites, shed epithelium, or white blood cells, pus cells and other substances in the urine after the infection, so it will cause the urine fishy smell heavy situation. It is also accompanied by stinging pain in the urethra during urination, frequent urination, urinary urgency or burning sensation in the urethra, which requires routine urine examination and urine culture examination to further confirm whether there is urinary tract infection. 2. If there is a kidney abscess, fishy smell of urine with fever and back pain will also occur during urination, and the urine can appear white and cloudy. Urine culture and ultrasound examination of the urinary system are needed to confirm the diagnosis of renal abscess. 3. Patients who have had urinary tract tuberculosis may also have a heavy fishy smell of urine, accompanied by symptoms such as cloudy urine, frequent urination and urinary urgency, and may be accompanied by night sweats and low fever. Patients mostly have a history of pulmonary tuberculosis and need to undergo chest X-ray, tuberculin test and antacid bacillus staining of urine.