Hatching duck eggs

[Tonia garner]

Hi I am hatching some cherry valley duck eggs day 6 and when i candled today one of My eggs is showing great veins but there is a small grey patch near the edge of the air sack is this showing bad news please

 

[CluckNDoodle]

It's really hard to know without looking at a picture. If you're unable to get a good image of it then I would simply sniff the egg to make sure it's not a ticking time bomb and if all is clear then put the egg back in the incubator to check in a few days to see if it has developed further. Good luck on your hatch!