How to judge the life state of goldfish in the fish tank? Happy or unhappy? Healthy or unhealthy? How to deal with the weak state?

The key is to have enough oxygen in the water. If the fish exhales on the water, it means there is no oxygen in the water. The solution is to add a circulating water pump to pump the water to the filter tank on the water surface, and then return it to the water tank after filtering with filter fiber cotton. This can not only bring the oxygen in the air into the water, but also filter the dirt in the water. Then change the water every 3-5 days, and change the water no more than half at a time. Healthy and unhealthy is generally to observe whether there are spots on the skin of fish. If there are spots, they should be isolated in other tanks, and a little potassium permanganate should be added to the water tank for disinfection. If the situation were not serious, they would still be alive.