The water quality requirements for goldfish are as follows:
pH Value: Goldfish can tolerate a pH range in water from 5.5 to 9.5, but they prefer water that is slightly alkaline. The ideal pH range is between 6.5 and 8.0. Some also believe that a range of 7.5 - 8.5 is more suitable.
Hardness: Goldfish prefer water with a hardness between 150 - 300mg/L. Some people think the suitable hardness range is GH 5 - 19 dH and KH 3 - 10 dH. Such hardness is beneficial to their growth.
Ammonia - Nitrogen and Nitrite: Ammonia - nitrogen and nitrite are harmful substances produced by the decomposition of goldfish feces and leftover bait. They are toxic to goldfish. Regularly test the ammonia - nitrogen and nitrite content in the water to ensure they are within the safe range. Generally, ammonia - nitrogen should be less than 0.02 mg/L, and nitrite should be less than 0.1 mg/L.
In addition, the water quality for goldfish should also meet the following conditions:
Dissolved Oxygen: During the fry stage or when the weather is hot and stuffy, the dissolved oxygen must be above 5 mg/L. Under normal circumstances, the dissolved oxygen should be above 4 mg/L. Sick fish should be raised in water with a dissolved oxygen level above 6 mg/L.
Clear and Transparent: The water for goldfish must be clear and transparent without any turbid substances.
No Odor: The water should have no strange smell. This is one of the basic conditions for the healthy growth of goldfish.
Water Temperature Range: The suitable water temperature range for goldfish is 18 - 24 degrees Celsius. Avoid sudden changes in water temperature.
Moderate Water Flow: A moderate water flow can maintain the circulation of the water body, allowing goldfish to swim more freely.
In conclusion, to raise goldfish well, it is necessary to closely monitor and regulate various water quality parameters to provide a suitable living environment for goldfish.