1. It is a good idea to perform a frequent water change and cleaning schedule. Changing the water in your aquarium will keep it clean for the fish that live in the aquarium. Keep a full stock of the water treatment chemicals you will need for this purpose.
2. 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.
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.