Are my eggs unfertile?!?!

[Poultry_guy]

So I’m on the 12th day of 9 amerucana eggs. When I candle them(phone flashlight) about 7 of them was dark with large veins. The other ones I could only see the spots in the shell but not on bottom. Are they fertile?
Also, is it okay if their air cells are kinda smaller? I’m trying to lower the humidity.
Info:
Janoel 12 forced air incubator
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The ratio for fertility is 4 roosters and 20 hens
3 of the eggs were put in 15 hours later than the others

 

[Broodygranny]

If you have a good candler, and they are completely clear on day 12, then those ones are probably infertile. The ones with dark veins are developing, so I hope you get a great hatch!

 

[Mosey2003]

Are they blue or green shelled eggs? If any of them glow bright without veins, get them out ASAP. You want to remove clear ones that are those colors because they tend to have more porous shells and can be more likely to harbor bacteria and explode, and you don't want that.