How to Make a Terrarium in a Fish Tank? – 10 Steps (w/Photos)

how to make a terrarium in a fish tank

Most old fish tanks can end up in the trash, while they can be repurposed to make a homemade terrarium fish tank.

Creating a terrarium from an old fish tank can be a cost-effective way to make a unique and beautiful indoor garden since you already own the tank.

How to make a terrarium in a fish tank? There are some simple steps you can follow, including choosing a tank, adding substrate, and preparing some plants and decorations. Let’s keep reading to learn more!

What to Prepare to Build a Terrarium Tank

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  • A fish tank
  • Substrate (gravel, activated charcoal, and soil)
  • Sphagnum moss (Java or Sphagnum)
  • Decorative items (rocks, woods, etc)
  • Plants
  • Hot water, salt and soap
  • A sponge


Steps to Make a Terrarium in a Fish Tank

Step 1: Choose a fish tank

To turn an aquarium into a terrarium, the first step is to select a suitable aquarium.

It’s recommended to pick a tank that is large enough to accommodate the plants you want in your tank. However, you can make use of an old fish tank that is no longer in use if it meets your demands.

Knowing what type of plants you want to add to your tank also helps to pick a suitable tank. For example, if you plan to make a tropical plant terrarium, you should choose a tank with a lid to reduce water evaporation and increase humidity. If the lid isn’t available, you can customize one to size for you.

Step 2: Clean a fish tank thoroughly

Before turning an aquarium into a terrarium you should clean a fish tank thoroughly by removing any dirt or debris, using hot water and salt.

You can then clean the tank with a sponge and some soap. Then, let the tank dry completely before moving to the next steps.

Step 3: Make a gravel layer at the tank bottom


When setting up an aquarium terrarium, you need to add from 1 to 2 inches layer of gravel at the bottom for drainage. This is a crucial step in ensuring the health of your plants and preventing waterlogging.

Step 4: Add a moss layer


The next step is to add a moss layer on top of the grave. Java or Sphagnum are some of the most common moss right now. Before adding sphagnum moss you need to soak it for about 15 minutes and squeeze it out.

This layer helps to create a humid, retain moisture, and provide a natural and aesthetic look for your plant terrarium fish tank.

Step 5: Add activated charcoal for terrariums


Having a 1/2-inch layer of activated charcoal in a terrarium tank helps purify the air and water, and eliminate odors and fungi. There are many types of activated charcoal in the market, choose the best one and add a thin layer.

It is important to note that if you are using activated charcoal, it should be replaced every six months.

Step 6: Add a layer of soil mix


Now, add at least a 2-3 inches deep layer of soil mix to provide the plants with the necessary nutrients for healthy growth.

Soil mix is a combination of different types of soil along with other organic and inorganic materials that provide the appropriate pH and nutrient levels for the plants in the terrarium.

When adding soil mix, make sure to give the terrarium a good watering and compact it slightly to avoid air pockets.

Step 7: Decorate a terrarium

When decorating a terrarium, there are many different decorative items that you can use to create an exciting and visually pleasing environment for the plants. Some popular options include

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  • Rocks and stones: Adding stones or rocks can be a great way to enhance the natural look of the terrarium and provide a stable base for plants.


  • Wood: Driftwood, branches, or other types of wood help to create a natural-looking environment.


  • Miniature figurines: Some people like to include miniature figurines or other small decorative items to give their terrarium a unique, whimsical feel.


It is crucial to be mindful of the plants in the terrarium when selecting decorative items. Some decorative items could be harmful to the plants or could affect the humidity, light, or temperature levels.

Step 8: Set up a lighting system


Lighting is a critical component in converting aquarium to terrarium, as it provides the energy source for plants to photosynthesize and grow.

You can offer natural lighting for your plant by placing a terrarium tank near a window or where it can receive indirect or filtered light. But not in beams of the sun as direct sunlight quickly overheats the tank, causing harm to the plants.

Artificial lighting, such as fluorescent or LED lights, can be used to supplement or replace natural light if it’s not sufficient or consistent. Remember to install the light system before adding fish tank terrarium plants.

Step 9: Add plants

Before picking any type of plant to turn a fish tank into a garden, it’s important to know if these aquatic plants you plan to keep require the same living conditions or not.

The fern and cactus terrarium, for instance, have conflicting moisture requirements. Ferns need moist soil whereas cactus prefer their soil to be completely dry 90-100%.

If you are new and looking for fish tank terrarium ideas, making a succulent terrarium fish tank is such a good idea without too much effort as they can thrive in harsh environments with very little water.

Step 10: Monitor and take care of them

Finally, you need to monitor your terrarium carefully for the first week to see if they stay well or have any signs of disease.

Depending on which type of plants you keep in your terrarium you should find out what is the ideal living condition such as temperature and humidity. Don’t hesitate to remove any rotting plants or leaves to avoid causing bigger problems.

If you find these above steps complicated, you can use an aquarium to terrarium conversion kit to simplify the process. This tool will provide you with the necessary supplies and equipment to create and maintain a stable environment for your plants.



Can you use an aquarium as a terrarium?

Yes, you can use an aquarium as a terrarium or even a vivarium.

Whether it is a new aquarium or an old one, you can turn it into a terrarium with some simple steps. Indeed, it will require a lot of work to make the environment suitable for plants. However, don’t try the other way around, it’s completely risky to use a terrarium for fish.

Creating an aquarium terrarium combination is also a good idea if you don’t want to just keep some plants. This combo is quite similar to the paludarium which has both water and soil.

How to DIY set up a fish tank terrarium?

Here are the most basic steps to set up a DIY fish tank terrarium:

  1. Choose a tank: You can recycle your old tank or purchase large terrariums for plants.
  2. Create a base: Add substrate, activated charcoal, and soil mix
  3. Add some decorations elements: Rocks, stones, wood, and more to create a natural-looking landscape based on your aquarium planter ideas.
  4. Install lighting system: Choose an artificial light that is appropriate for the type of plants or use natural lighting.
  5. Add plants: Choose plants that are appropriate for the conditions in your tank, such as lighting and temperature. Plant them into the substrate, making sure to anchor them securely.
  6. Regular maintenance: Once the tank is set up, it is important to maintain a healthy plant environment.

What should I put in my water terrarium?

Here are three most common plant ideas to put in your tank terrarium!

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  •  Nephrolepis
  •  Adiantum
  •  Pteris
  •  Asplenium
  •  Peperomia
  •  Pellionia
  •  Marcgavia
  •  Epipremnum
  •  Sphagnum Moss
  •  Java Moss
  •  Sheet Moss
  •  Mood Moss
  •  Anubias Nana Petite
  •  Anubias Barteri Round


Many tropical plants can thrive in your terrarium, just make sure that they require the same living condition.


How to make a terrarium in a fish tank? Creating a terrarium in a fish tank is a unique and exciting way to display aquatic plants and animals. The process involves selecting an aquarium and choosing the right plants for the terrarium.

Setting up the terrarium requires proper lighting, and maintenance to keep the plants healthy. With a little research and attention, a terrarium fish tank can be a beautiful and low-maintenance addition to any home or office.