Decorating Your Aquarium

You have the option of creating two types of systems, a fish only system or reef tank system and this decision will impact the decoration of your tank. You must also take into consideration the substrate. While a substrate is not required in a saltwater tank, and some experts say that it will only trap waste and cause the nitrate level to rise, it does provide a certain esthetic appeal.

A fish only system basically consists of fish and not much else. The basic fish-only aquarium set-up usually consists of the tank, filter and lighting. This type of tank contains fish with possibly a little live rock, but no living corals or other invertebrates. You may include some dead coral living rock, inorganic rocks, imitation coral and seashells to dress it up a bit.

Coral and rock can be arranged to simulate a natural environment and include ample hiding areas, ledges, and crevices for the aquarium fish. Placement of the rock and coral should not be so complex that it will be difficult to remove uneaten food or debris during maintenance.

A reef tank consists of fish, corals, invertebrates and other organisms that live in a carefully balanced environment. For example, fish are selected for compatibility not just with each other, but with corals and invertebrates as well (i.e., fish are chosen that will not eat other desirable organisms in the tank). Reef aquariums are not for everyone; they are expensive to set up, furnish, populate and maintain. They are the most time-consuming, type marine systems you can have.


If you decide to use a substrate in your tank, the substrate (material to cover the marine aquarium bottom) should be selected carefully. Choose from crushed coral, dolomite, or aragonite gravel. If you’re not using an undergravel filter, fine-grain sand is another option. Some bottom materials used in freshwater aquariums are not suitable for a marine aquarium. Freshwater aquariums often use quartz gravel, epoxy-coated rock, or similar materials, many of which are dyed various colors. From an aesthetic point of view, coated or colored bottom substrates should never by used in marine aquariums. Colored substrates detract from the overall natural beauty of the aquarium and especially form the striking coloration of the fish and invertebrates.

Only substrates with a calcareous composition should be used for marine aquariums, since they are the only types that have the capability of buffering the water. The most commonly available appropriate substrates include natural coral sand, limestone, oyster shell, and dolomite. A combination of calcareous materials can also be used for aquascaping the aquarium bottom.

Amount of Required Substrate

The amount of material for an aquarium is mainly dependent on whether you are using an undergravel filter. It is highly recommended that you include an undergravel filter as standard equipment for your first aquarium.

With an undergravel filter a recommended depth of bottom material is 2.5 to 3.0 inches (6.2-7.5 cm). This will ensure that you have ample material for proper filtration through your biological filter. You may make the bottom material deeper, but do not make it less than the stated guidelines.

In aquariums without an undergravel filter, a shallow layer of substrate is all that should be used to cover the bottom, with a depth of not more than 1/2 to 3/4 of an inch (1.2-2 cm) of substrate. The size substrate in this situation is not as critical as with aquariums with undergravel filtration.


It is important to note that not all rock is safe for aquariums. Many contain quantities of soluble metal salts that can quickly kill marine animals. Only rock that has been purchased should be used in a marine aquarium. Do not use any rock that you have collected unless you can be assured that it is nontoxic. All rock should be washed well to remove any sand or dirt prior to adding to your aquarium.

Natural Coral

The most frequently used decorative item in a marine aquarium is coral. Various types are available, including brain coral, finger coral (Porites), staghorn coral, and organ pipe coral.

Any purchased coral should be soaked in fresh water prior to use to ensure that all organic material has been cleaned before placement in aquarium. Coral from pet shops is often pretreated and cleaned prior to sale. Such coral can be used after it has been rinsed to remove any dust or other materials that have adhered to the coral skeleton. However, it is still recommended that you subject it to a special cleaning process. This ensures that all organic material has been removed from the coral prior to placement in the aquarium.