Keeping goldfish can be both easy and difficult. If you don’t understand what goldfish eat, what kind of water they prefer, and what they are afraid of, you might not be able to keep them well, and they may die soon. For example, if you use clean sand-filtered water to keep goldfish, they may die. Why is this?
Anyone who has kept goldfish knows that their best food is live “bloodworms.” Bloodworms are only the size of sesame seeds and grow in fertile water pits. Bloodworms feed on tiny animals. When you filter water through clean sand, most of the organisms in the water are removed. If you don’t add additional food to the sand-filtered water, the goldfish will starve because there’s nothing to eat. The bloodworms, living in filtered water without food, will also starve and die soon. When the bloodworms die, they spoil the water. If you don’t change the water, the goldfish will die quickly due to the unsuitable environment.
In addition to this, when changing the water, you should let fresh water sit for a while. Fresh water is different from the water in the tank, and the sudden change can cause the goldfish to die from the shock of a different environment. Letting the fresh water sit allows its temperature to gradually match the tank water, making it easier for the goldfish to adapt.