When you decide to start an aquarium as a hobby or even a more dedicated and time-consuming vocation, the kinds of fish to put in your tank is always the first decision to be made.

Freshwater Aquarium Gravel

After selecting an aquarium of the appropriate size for the fish you will be placing in it, the next decision should be what type of freshwater aquarium gravel to place in the bottom of your tank.

Also commonly referred to as substrate, the kind of gravel you choose can have a substantial impact not only on the visual appeal of your tank but also the well-being of your freshwater fish and any live plants you place in the habitat.


Gravel vs Sand?

Gravel is the most popular type of aquarium substrate, with one of the biggest reasons for its popularity being that is comes in a wide variety of colors and particle sizes, with the choice of colors being why it is preferred by young children who are taking up an aquarium as a hobby.

Another reason gravel is preferred over sand is that it is easier to clean. Sand is of such a fine consistency that it frequently gets sucked into tank vacuums.  Also, some fish like to sift the substrate and sand can be an irritant due to its small particle size.

How much gravel should I get?

The recommended level of gravel for tanks up to 55 gallons is a two-inch layer.  For tanks larger than 55 gallons, two to three inches should be sufficient.  Shallow layers of freshwater aquarium gravel can be unattractive, and deeper layers can be much more difficult to clean.

What color should I choose?

Colorful Gravel

Rainbow Gravel

The choice of color is strictly a personal one, but there are some factors you may have to first consider.

Many fish appear to be more colorful with a darker background, so if you have flashy or boldly marked fish, you may want to choose a dark color as your freshwater aquarium gravel.

Fish behavior is generally unaffected by the color of their tank’s substrate, but some fish behave less timidly with darker gravels and some fish get spooked more easily with lighter-colored substrate.

Larger gravel vs smaller gravel?

The key difference between large particles and small ones in an aquarium is that larger particles allow more unconsumed food and biological waste to slip between the gaps and cracks. This can lead to potentially harmful toxic build-up if the tank is not cleaned properly on a regular basis.

Conversely, smaller particles can compress more easily, which creates localized areas in the tank’s substrate that are lacking oxygen.

Make sure the fish you choose do not have particular habits when it comes to interacting with the substrate in their habitat as this can affect the overall health of your fish, as well.

Another important thing to consider is the freshwater plants that you plan on having in your freshwater aquarium. If you plan on having live plants in your aquarium, it’s best to avoid larger gravels and opt for finer gravels instead.

Gravel Size

How can the gravel substrate potentially harm my fish?

If you have fish who like to sift the sand or gravel to find food particles, this can potentially cause them harm because very fine particles can be an irritant and larger particles may have jagged edges that could injure the fish.

Also, fish that burrow into the substrate can encounter injuries for the same reason – jagged edges on larger gravel pieces.

Should I clean the gravel regularly?

You should only need to clean all the freshwater aquarium gravel when you are first setting up your tank and putting the gravel in it.  This cleaning should be done by rinsing the gravel with warm to hot water until the water runs clear, and will remove any manufacturing or packing dust and debris that may have adhered to the gravel.

How should I clean my tank’s gravel, and how often?

Aquarium Vacuum

Mr. Cleaner – Aquarium Vacuum

You should clean your freshwater aquarium gravel no more often than once a week, possibly less frequently depending on how many fish are occupying your tank and how much uneaten food debris and biological waste is gathering at the bottom of the aquarium.

When you do clean your tank’s gravel, use a gravel vacuum and clean approximately 30% to 40% of the freshwater aquarium gravel at each cleaning.  This is the same volume recommendation for how much water to siphon out of the tank in exchange for fresh water.

The most important thing to do when choosing freshwater aquarium gravel for your tank is to research the habitat preferences and requirements of the fish you will be placing in the tank first.  If your fish have no specific substrate needs, you can pick and choose based on your own preferences and set your tank up in a way that is completely pleasing to your eye without negatively affecting the fish.

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Having many years of experience in keeping different types of fishtanks I'm glad to provide valuable content for the beginners and more experienced fishtank keepers.