You have the right idea, well almost. First the tank looks great, but if you are serious about spawning them and raising fry you will need to move the adults and any other fish after they spawn. Like most egg layers, except cichlids, Danios eat eggs as fast as they can find them. The likelyhood of any eggs surviving to hatch in your set up would be very low. Should a few lucky eggs make it that far, the parents would pick them off as a snack ASAP. Danios are egg scatterers, so they will drop eggs all over and in the plants. Their eggs are not too sticky so most end up on the bottom.
If you condition the fish and use a spawning tank you're likely to get a large number of fry. I mean hundreds, maybe more. When I spawned them I conditioned the adults for 2-3 weeks. What I did was kept the group well fed and watched for females getting bloated with eggs. I removed the females and allowed them to drop eggs without males. I siphoned off the unfertilized eggsa sn conditioned them again for a couple of weeks. Live baby brine shrimp works best with fast results. When the females are full of eggs again, I set up a breeder 10gal. I added water, a heater, sponge filter and placed a layer of marbles on the bottom. You can use a plastic grate instead of marbles. I placed some wieghted plastic plants over the bottom and added the breeders in the evening. I feed them and two hours later it was lights off. When the lights came on in the morning I watched as the males drove the females into the plants. I gave them a few hours and pulled all the adults putting them back in their tank. If memory serves me, the eggs hatch in 48 hours or less. The fry don't require food for 48-72 hours befor ethey are free swimming. They then need green water for the first 4-6 days after which you can add micro worms or live baby brine shrimp. Keep the rearing tank clean using a piece of airline as a siphon and do water changed of 5%-10% 1-2 times daily for the first two weeks. They grow quckly and within 4-6 weeks can join the big fish. As with many egg layers, only keep and raise as many fry as you want and have room for. These guys will have a ton of eggs and raising them all outside a commercial set up is not feasable. Worst case, they are so over crowded they pollute the water and everyone dies.
This is a great project for a summer time kiddie pool to raise fry!! Good luck.
or even a lone betta could be fun! Good luck!
