Overfeeding in koi can be identified through comprehensive observation.
First, check for uneaten food: if significant amounts of leftover feed remain floating on the water surface 5 minutes after feeding, it is a clear sign of excessive feeding.
Second, observe fecal condition: healthy koi feces should be short, thick, solid, and sink to the bottom. If you notice white mucus-like feces, loose floating feces, or feces with bubbles, it indicates overfeeding and poor digestion.
Abnormal fish behavior is another signal of overfeeding, such as frequent gasping at the surface (indicating oxygen deficiency), lethargy, resting at the bottom, or even rolling to one side after feeding. Rapid deterioration of water quality, especially a sudden spike in ammonia or nitrite levels within 24 hours, also suggests overfeeding, as uneaten food decomposes and pollutes the water. Finally, long-term signs of obesity should be monitored, including a thickened back ridge, fat accumulation between scales, and abnormal swelling in the liver area (a risk factor for fatty liver disease).
Eating too much causes eyes to bulge.
For novice keepers, it is recommended to start feeding at 1% of the koi’s body weight and gradually increase to 1.5%–2%, ensuring each meal is consumed within 3 minutes. Additionally, implementing a weekly fasting day helps promote digestive system recovery and overall health. Regular monitoring and adjusting feeding based on seasonal changes and fish activity levels are essential to maintaining optimal health and water quality.
