Pond fish may stay near the bottom due to cold water, poor water quality, low oxygen levels, stress, or illness. This behavior is often normal during winter but may indicate a problem during warmer months.
Common reasons fish stay at the bottom
- Cold water: Koi and goldfish become less active as water temperatures drop, especially below 50°F (10°C).
- Poor water quality: Elevated ammonia or nitrite levels can cause fish to become stressed and inactive.
- Low oxygen: Insufficient dissolved oxygen can cause lethargy and abnormal behavior.
- Stress: Sudden temperature changes, predators, or disturbances may cause fish to hide or remain near the bottom.
- Illness or parasites: Fish may remain at the bottom when experiencing health problems, often accompanied by clamped fins, loss of appetite, or abnormal swimming.
What should I check?
- Water temperature: Determine whether reduced activity is normal for the season.
- Water quality: Test ammonia, nitrite, nitrate, and pH levels.
- Aeration: Verify that the pump, waterfall, and aeration system are operating properly.
- Fish behavior: Check for clamped fins, sores, abnormal swimming, or loss of appetite.
- Pond conditions: Remove excess debris and decaying organic matter.
When should I be concerned?
Fish resting at the bottom during cold weather is generally normal.
Fish lying on their sides, remaining unresponsive, or showing signs of distress require immediate attention.
If abnormal behavior continues after checking water quality and oxygen levels, consult a veterinarian or aquatic fish health specialist.