The red mouth of the fish is probably caused by fighting. There are many kinds of fish. Different fish have different temperaments, some are gentle, while others are fierce. For fish with big temper, fighting is inevitable, and fish usually attack with their mouths, so their mouths are easily injured. Usually, after a fight is found, it is necessary to isolate it in time to avoid them fighting too hard.

If the water quality in the fish tank is not good, the fish may also turn red in its mouth. This condition is also called hemorrhagic disease, which is a common fish disease. If you want treatment, the simplest way is to change water and improve the water environment, and the fish will recover slowly. During daily feeding, water should be changed regularly to avoid deterioration of water quality.

As a temperature-changing animal, fish is not very adaptable to temperature. If the temperature changes suddenly, it will also be stimulated, and its mouth will turn red like bleeding. In view of this situation, we must pay attention to temperature control and keep the temperature constant. Especially for raising tropical fish, it is necessary to control the temperature above 20 ℃ with a heating rod.

When fish are infected with germs, their mouths will also turn red like bleeding. At this time, don't take medicine in a hurry. First, use the old three methods to treat it. If it can't be cured, consider soaking it with medicine. Pay attention to the dosage of medication. Too much will cause drug damage to fish and endanger its life.