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Can Moss Grow Underwater? (Read This First!)

Mosses are flowerless, non-vascular small plants that belong to the Bryophyta taxonomic division. Mosses generally form dense green clumps in the shady and moisture-enriched environment.

This article will provide an in-depth answer and offer you deep insights into the habitant of mosses – whether moss can grow underwater or not.

Can moss grow underwater?

Yes, moss can grow underwater. Moss can be grown in the aquarium and you can cover the aquarium garden with them. Moss can grow on the rocks and then you can transfer the rock containing mosses underwater. They will thrive. But you have to slightly trim the moss occasionally to control the growth.

Moss can grow underwater. A lot of terrestrial mosses survive underwater. You can grow many land moss species in your home aquarium and the mosses will survive. Moss can grow on the rock. Thus you can grow moss without soil. 

In order to grow moss in a water tank, all you have to do is to transfer the land moss rock into the tank. Here, we have described some moss species and their habitat –

Sphagnum moss:

Sphagnum moss is also known as peat moss. They can thrive underwater. Sphagnum moss is mostly used as peat. They are fibrous and stingy and easy to grow underwater.

Terrestrial moss:

Not every type of terrestrial moss can grow underwater. Some species of terrestrial moss can grow in the water tank but many land species of moss can only thrive in terrestrial areas.

Irish moss:

Irish moss grows inland areas. Irish moss is not well adapted to the water environment. Irish moss can sustain about a week under the water.

Pillow moss:

Pillow moss is another terrestrial moss that grows in the land areas. Pillow moss can not survive in the water. Pillow moss species are not evolved for growing in water. For this reason, they can survive underwater.

Peat moss:

Peat moss can grow underwater. They have many beneficial effects- growing peat moss in the water tank reduces the pH of the water. Peat moss removes the contaminant from the fish tanks.

Scotch moss:

Scotch moss can grow underwater as long as you don’t submerge it in the water.

Java moss:

Java moss can grow underwater. You can identify the java moss from their bright green leaves. Some java moss also grows in the land.

Regular moss:

Some regular land moss can grow underwater. But not all mosses can sustain in the water environment. Only some species of regular moss thrive in the water tank.

Can I put moss in my fish tank?

Yes, you can put moss in your fish tank. Fish tank often fills up with contaminants. The contaminants come from fish waste, skin, feed particles, and many more. 

This often pollutes the fish tank environment and reduces the amount of dissolved oxygen in the water tank.

You can grow moss in the fish tank. You can put peat moss in your tank and the moss will thrive in the water environment. The peat moss has several beneficial effects. The moss will clean the water.

Peat moss absorbs all the contaminants from the water and reduces the pollution of the water. The peat moss also increases the water quality by enhancing the dissolved oxygen level in the water tank. Often fish and other contaminants rise the water pH. This is harmful to the fish. 

Peat moss reduces the pH of the water and creates a neutral water environment.

How to grow moss underwater? How to grow land moss in an aquarium?

You can easily grow moss underwater. And many land moss species thrive in an aquarium environment. The step by step procedures to grow moss underwater are listed hereafter –

Tank setting up:

First, you have to set up a tank. You can purchase smaller than 19 L fish tanks to grow moss as well as fish. Keep the water temperature between 21° to 24°C. Moss can withstand low temperatures, but their growth decreases. Adjust the pH of the tank to 5 to 8.

Adding moss in the water tank:

You can put aquatic mosses in the water tank. Java moss is an aquatic moss and it will easily grow underwater. But land mosses such as peat moss, scotch moss can also grow in the water tank. Drop the moss on the water surface if you want the moss to float.

You can also grow the land moss on the rocks and then transfer the rock to the water tank. This process is followed in order to grow land moss in the water tank.

Trim the moss:

Sometimes you have to trim and shortly cut the mosses if the plant grows too long. You can use clean pair of scissors to slightly trim the mosses. But always use sterile scissors to trim the mosses as contaminants attached with the scissor can harm the plant. 

It is better to trim the moss once a week.

Replacing the moss:

Replace the moss if the algae start to grow on it. But if you insist to keep the old moss in your aquarium, then you have to clean the algae from the moss using a toothbrush.

Tank requirements for moss growth:

Mosses are susceptible to contaminants and detergents. A special tank requirement is needed for the growth of moss. The tank requirements for the moss are explained hereafter –

Water tank size:

You can grow the moss in a water tank less than 19L in size. You can also grow fish in that water tank. The tank should be big enough for the moss to grow.

Water temperature:

Water temperature is an essential requirement for moss growth. 21° to 24°C is the optimum water temperature for moss growth. Though moss can grow at low temperatures the moss growth decreases. 

That’s why maintaining an optimum temperature is necessary for moss growth.


It is best to maintain the pH level of the aquarium within 5 to 8. You can adjust the pH of the water by mixing chemicals. You can easily purchase pH adjustment chemicals from the local store. An acidic environment is toxic to the moss. 

If the pH falls, you have to increase the water pH.

How to maintain moss in a tank?

Moss is easy to grow. Moss grows in both water and land areas. To grow land moss in water, you have to transfer the rock containing moss into the water tank. And moss such as java moss, peat moss grows in water. As the moss grows in water, you have to maintain the moss in a tank.

Here, we have described the maintaining procedures of moss in a tank –

Water temperature:

You have to maintain optimal water temperature in the aquarium. Mosses thrive finest at 21° to 24°C temperature. Moss grows slowly at low temperatures.

Trimming the moss:

You have to trim the moss every week if the moss is getting too long. You can slightly trim the moss using a scissor. But be sure to clean and sterilize the scissor before use as the scissor can pass contaminants into the water.

Replace old moss:

Replace the moss if algae start to grow on the moss surface. Algae forms in the water due to poor water circulation and light. You can also remove the algae from the surface of the moss using a toothbrush. 

But often removing algae is hard and replacing old moss with new moss plant is easier.

Water pH:

You have to maintain pH 5 to 8 for growing and maintaining the moss population. Though moss neutralizes the pH of water, it is better to adjust the pH to an optimal level. Acidic pH is not desirable in the water tank as well as basic pH. 

You have to balance optimal pH in order to find the highest moss growth.

Oxygen level:

Moss improves the water quality of the tank. But even though mosses increase the oxygen quality in the water, maintaining an optimal oxygen condition in the tank is always recommendable.

How fast does underwater moss grow?

Some moss grows faster than others. Underwater moss for example the java moss grows 1 to 1.5 inches every month. Aquarium moss is a slow grower and they grow slower than land moss. Java moss can reach 2 to 4 inches in height and it grows slowly in the new environment.

When the moss is transferred to a new environment, the growth of the moss decreases. Moss grows slowly in the new condition as it takes a few weeks to adapt to the new environment. Java moss can grow 1 to 2 mm in size every day. But java moss isn’t the fastest-growing moss.

Final thoughts

Moss can grow underwater. Moss is easy to grow and needs little nurture. Some aquatic moss species such as java moss, scotch moss grow underwater. But some regular moss species can also thrive in the water environment. Moss removes contaminants from the polluted water and increases water quality.