Last month we went over the behavior after the spawn. This month, we will go over the hatching of the eggs. Next month we will go over how to raise the fry.
Flowerhorn have large Spawns and there can be 100 to 600 eggs.
After 48 to 72 hours, depending mainly on water temperature, the eggs will begin to hatch. Only the dark ones will hatch. They are dark because after about 36 hours, the eye starts to develop and will show through the egg sack. Most of the fry will stay attached to the surface where the eggs were laid via a small membrane on their head. A few will become detached and will fall to the bottom. At this point the fry will look like a small comma to the naked eye. Under magnification, they are quite ugly and will look like something straight out of a monster movie.
They will remain attached to the substrate for another 48 to 72 hours. There is not much to do at this point. They will have an egg sack and will live off of it during this entire time. The main concern is fungus. Adding Methylene blue to the water will mostly solve this. If you are going to artificially raise them, and have taken the parents out of the tank, you should add aeration about one inch from the fry to keep the water moving around them. They will start to become free swimming about 2 to 3 days after hatching.