Why is Gravel or Substrate Required in an Aquarium?

Goldfish in a fish tank with green gravel

Aquarium gravel, also known as substrate, enhances the appearance of a tank and comes in a range of colors and sizes, ranging from little pebbles and sand to massive river boulders. However, aside from aesthetics, it provides a number of crucial functions, albeit substrate isn't always the best option.

What is Aquarium Gravel?

Substrate refers to aquarium gravel or any other material placed on the tank's bottom. Beneficial bacteria live on the substrate of your aquarium and help to keep the water clean by breaking down fish waste, leftover food, and plant debris.

Biological Filtration

Biological filtration for beneficial bacteria is maybe the most significant purpose aquarium gravel performs. Although bacteria can survive without a comfortable gravel base, they may not develop in large enough numbers to maintain your aquarium safe for your fish.

If the tank's bottom is left exposed, it will be required to replace the water more frequently to prevent dangerous trash from accumulating. Even frequent water changes may not be enough to keep ammonia and at bay if the tank is highly filled.

Fish Habitat

Substrate is an important component in creating a nice environment for your fish. It provides hiding places for fish, especially those who like to burrow, as well as enrichment for bottom-dwellers who prefer to rummage through the substrate for morsels of food. Additionally, it aids in the reduction of reflections within the tank, which can stress fish.

Substrate can also help to enhance the water's chemistry. If your fish demand hard water, for example, a coral substrate can assist you in achieving the proper balance.

In addition, substrate can serve as a safe haven for fish eggs. Larger substrates allow eggs to fall out of the reach of ravenous fish who would consume their own spawn. Similarly, infusoria, or minute creatures, that may be present in the gravel substrate are an excellent first food source for newly hatched fish.

Home for Live Plants

If you have live plants, a substrate is second only to lights in terms of keeping them alive. In planted tanks, the right substrate may help your root and meet their nutritional requirements.

Laterite and vermiculite, which store and release nutrients for the plants, are frequent substrates for planted tanks. Typically, they're utilized in conjunction with gravel. Furthermore, certain aquarium plants with thicker root systems demand greater substrate depth, so keep that in mind while setting up your tank.

Aesthetic Appeal

You won't be able to see all of the microscopic ways substrate benefits your fish, but you will notice how it improves the overall visual appeal of the aquarium. Substrate hides garbage and other debris that might otherwise float through the water, in addition to adding a decorative component to the tank. Even if you only have a bare-bottomed tank for a day, you'll be shocked at how much "trash" accumulates on the bottom.

Substrate not only hides unsightly items, but it also highlights what you truly want to see: the fish. A silver fish, for example, does not show out well against naked glass. When viewed against a black background, though, all of its details stand out. Aside from making watching more enjoyable, substrate in a different hue from the fish lets you to see any health concerns or unusual behavior in your fish more clearly.

When Substrate Isn't Ideal

There occasionally are situations in which substrate isn't necessary or even desirable.

The most common reason for not using substrate in a grow-out tank is for hatching eggs and raising young fry. Grow-out aquariums must be kept immaculately clean, which necessitates frequent water changes and waste vacuuming. Fry are so little that they might be difficult to spot against a gravel substrate. As a result, cleaning the substrate or changing the water might easily suck them up.

In addition, hospital tanks frequently lack substrate, which can store infections that might stay and harm subsequent inmates. A tank with no bottom is an excellent approach to prevent this problem. Some owners opt to keep substrate out of quarantine tanks for the same reason.

Finally, some individuals feel that brightly colored gravel might stress fish since it does not resemble their natural habitat. Because stress can lead to a weakened immune system in fish, making them more prone to disease, you may want to err on the side of caution and choose a more natural substrate. Paint from the gravel can also leach into the water, so be sure any substance you choose is entirely fish-safe.