Fish Lying on Side at Pond Bottom: What to Do

New homeowner inherits 2×2 m pond with 9 fish (koi/goldfish). One fish lies on side at bottom, alive but struggling. Pump and waterfalls running.

First Steps

1. Check water temperature. If near freezing with ice cover, fish may be in torpor—do not disturb.
2. If water >50°F: Test ammonia, nitrite, pH, KH immediately.
3. Examine fish: Red streaks? Ulcers? Fungus? Parasites? Clamped fins? Excess slime?
4. Consider quarantine if only one fish affected and water params are off.

Cold-induced lethargy mimics illness. If pond is iced over, ensure a gas-exchange hole. If water is warm and params normal, a vet scrape is needed. Don't medicate without diagnosis.