brocade carp change water once every seven days. Raising koi fish is the same as raising other fish, and it is necessary to change water regularly. If the fish tank is large, the number of fish raised is small, and the filtration effect is good, the water quality is easy to maintain, and it is ok to change the water once every two weeks, but it is best to change it once a week. Every time you change water, you should change one fifth or one quarter. Too much is easy to stimulate fish. In addition, the temperature before and after changing water should be consistent.

1. Trapping water in advance: Before changing water for fish tank, the water should be trapped first. Because tap water is generally used for water change, although this water is relatively clean, it still has more chlorine, so it is necessary to remove chlorine by trapped water. Usually, after the water is connected, it needs to be put in the sun to dry for a few days, so that chlorine in the water will volatilize slowly.

2. Pumping water: To change water, you need to pump water first, find a pipe, lead it to the bottom of the cylinder, and then siphon water from it, usually about a quarter of it. If the fish tank is large and there is a lot of water to be changed, it can be pumped with a water pump, which is more efficient. After pumping, slowly add new water from the cylinder wall.

3. Precautions: In order to ensure the health of fish, the temperature before and after changing water must be consistent. Usually, before changing water, it is necessary to measure the water temperature first, and then allocate new water according to the measured data. The temperature difference between the two should be controlled at about 1 ℃, so that fish can adapt.