Koi fish should not be fed at night, and the main reasons are as follows:
Oxygen Requirement and Digestion
When koi fish digest food, they need to consume a large amount of oxygen. At night, due to the lower air pressure, the amount of dissolved oxygen in the water will decrease. Feeding them at this time may lead to a serious lack of oxygen in the water, thus endangering the lives of the koi fish.
Food Residue Problem
After feeding at night, the food may not be completely eaten. The food residues left in the water will ferment and consume oxygen, further worsening the oxygen deficiency in the water and affecting the respiration of the koi fish.
Physiological Habits of Koi Fish
Koi fish are usually in a resting state at night. Feeding them at this time not only cannot ensure that they eat normally, but also may produce harmful substances due to the decomposition of food residues, which has an adverse effect on the health of the koi fish.
Conclusion: In order to ensure the health of koi fish, it is recommended to feed them regularly and in appropriate amounts during the day, and avoid feeding them at night.