Could you tell me how to raise goldfish well? Thank you

On the contrary, it's easy to raise goldfish. The basics is to have good aeration and filtration. Allow me to share with you what I know. First you have to know the capacity of your aquarium (how many gallons). The ideal ratio would be 1 goldfish for every 10-15 gallons. A overhead filter system is not expensive and will do the work. You just have to check the filter media everyweek if they're filled with sludge and cannot filter the water anymore. If you have space to place Bio Balls, do it, they help in the stabilization of the water too. As for aeration, you just have to make sure that the surface of the water is always disturbed to provide adequate oxygen for the fish. For smaller tanks (5 to 30 gallons), a small aerator connected to an air line to an air stone would be okay. I use a powerhead connected to an undergravel filter, then the water coming out of the power head is through a small pipe which is slightly above the water level. This agitates the surface giving the fish more oxygen. My fish are about 5" long and they're only about 6 months old. DO NOT CHANGE THE WATER EVERYDAY! This will kill the fish. They will go into shock. It is advisable to do a 20% water change everyweek. Sometimes, due to work, i cannot do the 20% water change. So instead i do a 50 - 70% water change every other month. The only thing i do after i finish putting in the new water is to put table salt in the aquarium. About 1 tablespoon for every 10 gallons, and about 100 drops of Methylene Blue. And that will last me for about 2 months or until the next water change. Well, i hope i was able to help you.

clear water and feed it to the right times is the most important and get a good habitate and biotope for them to fit in.