Put them in their own aquarium or confine them to a glass/plastic pot at the side of your current aquarium so they can't be attacked by others. Opening level to top of water
To put them in a nursery tank you have to see them, scoop them out and I do not watch the tank continuously. I sometimes glance up and see one being chased and eaten. I am not trying to raise them, just like to give them a chance to survive. Steve