Spring Pond Startup: When to Add Fish, Plants, and Chemicals in Michigan

In Michigan, with water temperatures in the low 60s °F, you can safely add hardy plants and goldfish—but hold off on feeding until temperatures stabilize at or above 60 °F. Fish metabolism slows below 50 °F; undigested food rots, poisoning the fish.

Startup Checklist

1. Fill with well water. Let it sit 24–48 hours to off-gas CO₂ and stabilize temperature.
2. Run the waterfall/pump. Oxygenates and circulates.
3. Add plants first: Floaters (hyacinth, lettuce) for shade; submerged (anacharis, hornwort) for oxygen; marginals for filtration.
4. Add a few feeder goldfish. Inexpensive, hardy, and they seed the biofilter.
5. Do NOT add chemicals unless a specific problem arises (ammonia spike, parasites).
6. Begin feeding only when water stays ≥60 °F day and night. Use wheat-germ-based food initially.

Build a simple biofilter (lava rock + filter floss in a tote) for long-term stability. Patience now prevents problems later.