New Preformed Pond: Goldfish Dying in Hours

New preformed pond, 5 feeder goldfish (99¢ each), 3 oxygen plants. 1 dead at 12 hrs, 2nd at 16 hrs. Asks: pond wrong? Remove rest? Fix?

New Pond Syndrome

No biofiltration established. Ammonia from fish waste → toxic in hours. "Oxygen plants" don't cycle ammonia.

Immediate Actions

1. Test ammonia NOW.
2. Large water change (50%) with dechlorinated, temp-matched water.
3. Add bottled bacteria (Tetra SafeStart, API Quick Start, etc.).
4. Stop feeding.
5. Add shelters (plants, rocks).
6. No full sun.

Root Causes

• Pond too small for 5 fish without filter.
• Feeder fish often diseased/stressed.
• No cycle = death trap.

Cycle the pond (4–6 weeks) before adding fish. Or add filter + bacteria + daily testing + water changes.