1. When breeding angelfish, it is normal for the first spawn to suffer heavy losses and not make it all the way to the hatching phase. You should have the proper equipment before you start to breed angelfish.
2. When adding new species to your aquarium, you have to ease them in. Adding too many fish too quickly can cause the ammonia and chemical levels to raise quickly. Adding fish slowly gives your filter time to catch up.
3. It is not considered a good idea to keep aggressive fish with fish of other temperaments. You should keep peaceful fish in an aquarium with other peaceful fish to avoid any sort of fighting between the fish. Aggressive fish should only be kept with other aggressive fish.