When the weather is sultry, why do the fish in the fish pond always swim close to the water?

The solubility of gas decreases with the increase of temperature and increases with the increase of pressure, so when the weather is sultry, the temperature increases and the pressure decreases, so there is less dissolved oxygen in the water, so fish should breathe more oxygen close to the water surface; So the answer is: the weather is sultry, the air pressure is low and the temperature is high, the solubility of oxygen in water is reduced, and fish should swim close to the surface to breathe more oxygen.