Observe koi behavior (Are they swimming normally? Eating? Social?)
Feed high-quality koi food (don’t overfeed)
Look for signs of stress or illness (spots, clamped fins, isolation)
Test water parameters:
Ammonia = 0 ppm
Nitrite = 0 ppm
Nitrate = < 40 ppm
pH = 7.4–8.5
Dissolved oxygen = 6–9 mg/L
Remove uneaten food and debris
Clean filters or check pump flow
Perform partial water change (10–25%)
Inspect pond equipment
Trim plants and clean off algae ( leave some for bio-balance)