A failed hatch is frustrating, but almost always explainable. Here are the most common causes and the checks to make for next time.
1. Infertile eggs
Without an active rooster or with a poor male-to-female ratio, many eggs are clear. Candling on day 7 confirms it: no blood vessels appear.
2. Incorrect temperature
Too warm and incubation speeds up and embryos die; too cold and it drags out and fails. Aim for 37.5 °C and check the incubator with a reliable thermometer.
3. Wrong humidity
Too humid and the air cell stays small and the chick drowns; too dry and it sticks to the membrane. Track air-cell growth at candling.
4. Not enough turning
Without regular turning until day 18, the embryo sticks to the shell. Turn at least twice a day, ideally three times, or use an automatic turner.
5. Poorly stored eggs before incubation
Eggs that are too old (over 7-10 days), kept warm or not turned lose hatchability. Store them pointy-end down at 12-15 °C.
6. Insufficient ventilation
The embryo needs oxygen. Closed vent plugs or a stuffy room can cause late-incubation deaths.
7. A disrupted lockdown
Opening the incubator after day 18 drops the humidity and can shrink-wrap the chick against the membrane. Keep openings to the strict minimum.
Diagnosing with candling
Candling is your best diagnostic tool. A clear egg on day 7 means a fertility problem. A blood ring signals early embryo death, often linked to temperature or poorly stored eggs. An embryo that develops then stops late in incubation points instead to humidity, ventilation or turning.
What to do after a failed hatch
Open the unhatched eggs, away from living areas as they can smell, to find the stage where development stopped: it tells you which period to fix. Then recalibrate your equipment, review your egg storage and log everything to compare with the next batch. A failure you analyse teaches you more than an unexplained success.