They've gone bad. Whether it is sea fish or freshwater fish, in the natural environment, it will deteriorate, especially in summer, a few hours will deteriorate and stink, freshwater fish should be slaughtered quickly after landing, cleaned, not in a hurry to eat, you can place the refrigerator for 24 hours, if you do not deal with it in a timely manner, the fish meat and thorns will be separated, and it is not fresh.