Fertile quail egg?

[FranzeskaPound]

This is my first time incubating jap quail. Anyone know if this is fertile?

. Day 5 incubation. The dark area is getting bigger

 

[nuthatched]

I don't see any veins but they could be too fine. Did you crack one open to check for the bullseye?

 

[FranzeskaPound]

Hiya no I haven't cracked one open to check . I might just wait and see . The shells are quite thick I can't even candle some of the darker shelled eggs