What Is Candling Eggs?
Candling is the process of shining a light through an egg to see what’s happening inside. Poultry keepers use it to check fertility, embryo growth, and overall egg health.
The term comes from the old days, when farmers literally used candles to check eggs. Today, we have LED candlers and flashlights that make the process easier and more reliable.
Why Candle Chicken Eggs?
Candling helps you:
- Check Fertility – See if the egg is developing after a few days of incubation.
- Remove Bad Eggs – Infertile or non-developing eggs can rot and contaminate the incubator.
- Track Growth – Watch embryos develop from tiny blood vessels to full chicks.
- Improve Hatch Rates – Removing problem eggs keeps conditions healthier for the rest.
How to Candle Eggs
You don’t need fancy equipment to start candling—just a good egg candler or strong LED flashlight.
Steps to Candle Eggs:
- Wash your hands before handling eggs.
- Darken the room for the best visibility.
- Hold the egg over the light—the large end works best.
- Look for signs of development, like veins, movement, or dark shadows.
- Handle carefully—eggs are fragile during incubation.
Tip: Practice with store-bought eggs first so you know what a clear egg looks like.
When to Candle Eggs
Timing is everything when candling. Candle too often, and you risk chilling the eggs. Candle too late, and you may not catch bad eggs in time.
Best Days to Candle Chicken Eggs:
- Day 7 – Check for veins and early embryo development.
- Day 14 – Look for movement and a growing dark mass.
- Day 18 – Final check before “lockdown” (when you stop turning eggs).
After Day 18, avoid candling—chicks are positioning themselves for hatching.
What You’ll See When Candling
- Fertile, developing egg – spider-like veins, dark spot moving around
- Infertile egg – clear, no growth after 7 days
- Early death (blood ring) – red ring around the yolk, no further growth
- Late-stage embryo – egg mostly dark with a large air cell
Note: Remove infertile or bad eggs promptly to prevent contamination.
Candling Duck, Quail, and Other Poultry Eggs
The process is the same for other birds, though duck and goose eggs are harder to see through because of thicker shells. Quail eggs, with speckles, may also be trickier. Use a high-powered candler for these species.
Tips for Successful Egg Candling
- Use a strong, focused light (LED egg candlers work best).
- Don’t candle more often than necessary—3 times is enough.
- Be gentle and quick to avoid chilling the eggs.
- Always check air cell growth—it should get bigger as the chick develops.
Final Thoughts: Why, How, and When to Candle Eggs
Candling is one of the most exciting parts of hatching chicks. It helps you:
- Confirm fertility
- Monitor growth
- Remove problem eggs
- Increase hatch success
Whether you’re hatching backyard chicken eggs, or experimenting with duck, quail, or goose eggs, learning how and when to candle will make you a more confident poultry keeper.