Medaka Journal
First prediction of hatch date (day 1) - 13 days
Second prediction of hatch date (day 2) - 8 days
Actual hatch date day 10
Heartbeat on day 4 - 83 beats per minute
Heartbeat on day 8 - 120 beats per minute
Heartbeat on day 9 - 190 beats per minute
Heartbeat on day 10 - 210 beats per minute

Day 1 stage 4: There are larger and fewer oil droplets, growth continues. The egg is 1.5 hours old.
Day 2 stage 20: The somites appear but you cannot see them from the angle of our picture. The embroyos' size has increased and the egg is 33 hours old.
Day 3 stage 22: The optic lens and cup are being developed and can be seen. The oil globes have formed into a large group and the egg is 40 hours old.
Day 4 stage 25: Tip of tail is out of yolk sac, some body movement and first recorded heart beat. The egg is 56 hours old and you can see the chorion membrane.
Day 7 stage 29: The eye is pigmented, the veins now take a twisted path across the egg instead of a straight path. The egg is 84 hours old. You can see the eye cup clearly and the oil droplet.
Day 8 stage 30: The bladder is developing, the heartbeat should be 140 beats a minute but we counted ours at 120. The egg is 102 hours old.
Day 9 stage 35: The spleen is a small red/crimson colored organ. Also there is a pigmented eye and the mouth moves freely, but cannot yet open. This egg is 200 hours old.
Day 10 stage hatching: The book says some will remain in there shell 1 to 3 more days. This egg is 264 hours old. In our picture you can clearly see the front of the fish and you can see its eyes. You cannot yet see the bladder in this picture. You can clearly see the melanocyte.
Medaka Videos

Day 1

Day 2

Day 3

Day 4

Day 7

Day 8

Day 9

Day 10

After hatching