For hardware description language file, see VHDL. VHD (Virtual Hard Disk) is a file format which represents a virtual hard disk drive (HDD). It may contain what is found on a physical HDD, such as disk partitions and a file system, which in turn can contain files and folders. It is typically used as the hard disk of a virtual machine.
Typically, koi eggs will hatch in less than a week. Koi eggs are very small, bead-like specks that can vary from milky white to yellow or green. Upon closer inspection, you can see two black dots through the transparent membrane of the egg. These are the developing eyes of the koi.
I am often asked how long it takes quail eggs to hatch. The incubation period for bobwhite quail eggs is 23-24 days. The incubation period for Coturnix (Japanese) quail eggs is 17 days. Here is a link for information about incubating japanese quail eggs.