1. It is generally recommended to use natural gravel for the aquarium. Colored gravel can be used, as long as it is professionally made, certain cheaply made color gravels can be toxic to fish in your aquarium.
2. 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.
3. Discus fish are very hard to care for, they have very specific care instructions. These fish are hard to care for but are very beautiful. However we recommend that these fish only be kept only by the advanced aquarium owner.