5 reasons aquarium gravel is ABSOLUTELY necessary!

Last Updated on July 4, 2021 by cmoarz

Aquarium gravel is one of the most important components of any aquarium. It is what creates a natural habitat for fish, it is where plants will grow, and it is what holds much of the beneficial bacteria in your tank together! Without this layer, things would get pretty messy. In fact, without gravel, your tank would surely perish quickly. In this blog post, we’re going to talk about 5 reasons why aquarium gravel is absolutely necessary!

Why is aquarium gravel necessary?

Aquarium gravel will help keep your tank clean as debris will be able to settle into nooks and crannies, It acts as a bacteria medium for beneficial bacteria that keep your fish alive, lowers the amount of fish stress, and act’s as a better fish habitat.

And that’s not even scratching the surface of the importance of a proper substrate.

As you can see, there are a plethora of reasons why aquarium gravel is necessary for your tank!

Many new hobbyists are under the impression it’s isn’t worth using, I NEED to dispel this myth right here right now.

What happens to an aquarium without gravel?

Without a layer of substrate, very few fish and plants can live in your tank. It is also impossible for any beneficial bacteria to grow outside of your filter.

This is important as this bacteria is what helps keep the water clean by converting ammonia into nitrite and then nitrate. Without proper levels of these two chemicals, toxins will start accumulating in the tank which can lead to death within days.


Furthermore, without substrate, there would be no natural ledges or hiding places for fish – making them feel incredibly vulnerable and stressed out when they should really have all the power over their environment as you do with your tank set up right now!

Another thing to consider. Without gravel, a lot of the particulate matter will have nowhere to settle and get eaten up by various bacteria and bottom feeders. This causes the water to constantly be cloudy and impossible to see threw after only a few days of having live fish in the aquarium.

Bare bottom tanks are not good to have.

Let’s get into the finer details of each of these points.

The Purpose of Substrate

is to:

– keep your tank clean by trapping debris in the gravel,

– promote good bacteria growth medium for beneficial bacteria is necessary for a healthy fish habitat and reduces stress on them as well.

– provide an environment where plants will grow very effectively.

What is this bacteria medium you keep talking about, I thought all bacteria was bad?


Bacteria is an important part of any tank. It is what keeps the water clean by converting ammonia into nitrite and then nitrate, which is a natural cycle that is crucial for your fish’s health!

Without it, You get a stagnant ammonia-filled aquarium which may as well be a vat of acid compared to clean water. This is very poisonous for your fish.

Without this needed cycle of bacteria reactions, our aquariums our oceans, our ponds, and our lakes would all be dead wastelands.

You might think you can just clean up all the poop before it gets too bad but trust me, it’s just not possible. When a fish digests food one of the main byproducts produced is ammonia – which is highly toxic to fish. Your filter can not remove ammonia on its own.

This is why it is so important for your tank to have a healthy cycle of good bacteria that can convert ammonia into nitrite and then nitrate.

That’s where this bacteria comes in, Not only does it seed itself inside the filter medium itself, But on every single porous surface in the tank, Including the gravel.

This effectively turns the gravel into a mean lean ammonia fighting machine.

Bacteria isn’t the only reason you should find aquarium gravel necessary either.

Fish Habitat, Safty and Healthy Plant Growth

When asking if aquarium gravel necessary It’s important to realize that there are other reasons aside from bacteria medium growth.

There are 2 important aspects of aquarium gravel when it comes to your fish’s stress levels.

In a natural habitat, No light comes from the bottom of the lake/ocean/river whathaveyou.

This is where the need for substrate becomes apparent. Without it, your fish will be scared all day and night because they can see light emanating and reflecting off the glass below.

The second reason is that aquarium gravel has a very important role in providing ledges or hiding places for fish so they don’t feel vulnerable anymore.

Not only do some fish like to burrow into the gravel itself, but It also gives a place for plants to root, and with solidly rooted plants you get plant coves and plant cover for your fish to hide in!

Some species of fish are even only bottom feeders, and without something to catch all that food, they might starve to death. This is true for plant algae grazers as well.

Please do not skip on this absolutely necessary component of an aquarium setup – It literally is life-saving to have good quality substrate in your tank!

Some extra tips when it comes to picking a substrate

Hopefully, we answered your “is aquarium gravel necessary” question, yes it ABSOLUTELY is! So with all this said and done, What are some tips and things to consider when going out to purchase some aquarium substrate.

Tip 1: Avoid vibrant and colorful gravels. Stick to natural darker colors. Our recommendation for a top layer is Fluval volcanic rock. It’s completely filled with every nutrient an aquatic plant could need, It’s light and your fish will love to dig around in it. Most importantly, It’s a natural color and shape which will reduce stress in your fish. It also helps bring down pH if you need less hard water. (You can compensate for this easily if you need harder water with a cuddle bone or crushed coral placed in your filter).

Tip 2: Layer your substrate. In most cases, I would recommend a layer of sand, a layer of Fluval, and a small layer of aquarium-safe pebbles on top of the Fluval. It should be at least 3 inches deep.

Why so complicating? Well, it gives a much more natural appearance and it looks beautiful from the outside. It also allows better bacteria growth, waste management and gives plants a much easier time to root nice and deep and sturdy.

Why not put the sand on the top? Because many species of fish do not like sand. Gastropods and shrimp also hate it. It’s much better to have a layer of sand underneath rather than on top unless your specific species of aquarium habitants require sand.

If you have a mix of both sand critters and none sand critters, You can do a half and half which also looks amazing when set up properly with a bit of driftwood and proper plantings.


Owner of AquariumGravel.com and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!