On the subject of beautifying your custom fish tanks it is important to consider some different kinds of rock, coral and also other hard accessories. The type of fish tank you intend setting up will have an impact on your final decision as will the type of fish you are going to acquire.
If you are setting up a marine fish tank and have some money to spare it is important to buy some Lava Rock. This does not come from a volcano as suggested by its name but it may be man made especially for use in an aquarium. It can be ideal for putting in rock formations in a salt-water aquarium.
Slate is ideal whether or not you intend setting up freshwater or saltwater custom fish tanks. It is heavy and you must get the type that is suitable for use in an aquarium but fish will use it for spawning. They are going to also take pleasure in combing through any caves or formations you have constructed with the slate.
If you are buying coral you can purchase the artificial version not least because the importation of coral is illegal in some countries. Coral is lovely and really does add to the appeal of a marine aquarium tank. Don't use wood as the dangers of poisoning your fish are too high. If budget is a problem don't be silly enough to use gravel that you found in the garden unless it has been scrubbed, disinfected and made suitable for use in custom fish tanks. You will not always see the dangers posed to your fish and it is terrifying how easy you can eradicate your fish colony by using an unsuitable materials. So be careful!