Scald is koi fish pine scale disease or ascites scale disease, which has a high mortality within 48 hours and must be treated immediately. The diseased fish can be fished out, soaked in 3% sodium bicarbonate and 2% saline solution for 10 minute, and then fished out and isolated with yellow powder and gentamicin (oxytetracycline, chloramphenicol and chlortetracycline) combined with five thousandths of saline for a long time, during which oxygen is blown, and water is changed in stages for 3-3 minutes.