The oxygen pump of tropical fish is broken.

Remove the water pump and clean it. As long as it is not hoisted out of the water, the motor will not burn out, but it may also burn out due to long-term overload (too much dirt makes it difficult for the wing wheel to rotate). If it still doesn't work after cleaning, buy a new one. The water pump is sealed, and non-professionals can't repair it, even if it is more expensive than buying one! Try to choose famous brands, such as Risheng.