How To Make A Terrarium In An Aquarium: Your Complete Guide

Written ByHoward Parker

Ever look at your beautiful aquarium and think, “What if I could grow something above the water line, too?” You’re not alone. Many of us in the hobby dream of blending the lush, green world of a terrarium with the vibrant, flowing life of an aquarium.

It feels like it should be complicated, right? Two different ecosystems, one glass box. But I promise you, it’s more achievable than you think. This is your ultimate guide on how to make a terrarium in an aquarium, transforming your tank into a breathtaking slice of nature called a paludarium.

In this post, we’ll walk through everything, step-by-step. We’ll cover selecting the right supplies, building your land and water zones, choosing the perfect plants and animals, and keeping your new world thriving for years to come. Let’s build something amazing together.

What is a Paludarium? The Best of Both Worlds

Before we dive in, let’s clear up the terminology. When you create a terrarium inside an aquarium, you’re building what is known as a paludarium. The name comes from the Latin word palus, which means “marsh” or “swamp.”

Think of it as the perfect hybrid. It’s not just a fish tank, and it’s not just a box of plants. It’s a single, cohesive ecosystem that features both a significant water area and a land area. This setup allows you to keep aquatic animals, semi-aquatic animals, and moisture-loving terrestrial plants all in one display.

The benefits of how to make a terrarium in an aquarium are huge. You create a visually stunning, multi-level display that mimics a real riverbank or tropical shoreline. It’s a fantastic way to build a more naturalistic, self-regulating environment, making this a truly sustainable how to make a terrarium in an aquarium project.

Gathering Your Supplies: The Foundation of Your Ecosystem

Like any great project, success starts with having the right materials on hand. Don’t worry, you might already have some of these! Here’s what you’ll need to get started.

Choosing the Right Tank

You can start with a new tank or convert an existing one. Taller tanks, like a 20-gallon high or a 40-gallon breeder, are often ideal because they give you more vertical space for the land portion to rise above the water.

A standard glass aquarium works perfectly. Just make sure it’s watertight and has no cracks. A tight-fitting lid is also a must-have, especially if you plan on keeping any animals that can climb or jump!

Building the Land Area

This is where your creativity comes in! The goal is to create a stable landmass that is physically separated from the water section. Here are a few popular methods:

  • Hardscape Method: Use large pieces of aquarium-safe driftwood, cork bark, or rock to build a landmass that rises out of the water. You can stuff gaps with moss to create pockets for planting.
  • Substrate Slope: Build up a slope of gravel or lava rock, held back by larger rocks. This is simple but can be prone to erosion over time.
  • Divider Method (My Favorite): Use a sheet of acrylic or “egg crate” (a plastic grid used for lighting) cut to size. You can glue it in place with aquarium-safe silicone to create a permanent, clean barrier between land and water. This gives you the most control.

Substrate Layers for Land and Water

Creating proper substrate layers is one of the most important how to make a terrarium in an aquarium best practices. It prevents the land area from becoming a soggy, anaerobic mess.

For the land section (from bottom to top):

  1. False Bottom: A 1-2 inch layer of lightweight clay pebbles (LECA) or lava rock. This creates a space for excess water to drain into, protecting plant roots from rot.
  2. Substrate Divider: A piece of fiberglass mesh screen placed on top of the false bottom. This prevents your soil from falling into the drainage layer.
  3. Terrarium Soil: A mix of sphagnum moss, peat, and coco fiber (often sold as ABG mix) is perfect. Avoid standard potting soil, as it contains fertilizers that are harmful to aquatic life.

For the water section:

You can use any aquarium-safe substrate you like! Sand, fine gravel, or aquatic plant soil all work wonderfully, depending on the look you’re going for and the plants you want to keep.

Essential Equipment

Your equipment needs are a hybrid, too. You’ll need:

  • A Filter: A small internal filter or a canister filter is ideal. Canister filters are great because you can hide the intake and position the outflow to create a waterfall over your landmass!
  • A Heater: If you plan on keeping tropical fish, a submersible aquarium heater is necessary.
  • Lighting: You’ll need a full-spectrum LED light that is powerful enough to support both your aquatic and terrestrial plants. A light with a built-in timer makes life much easier.

The Step-by-Step Guide: How to Make a Terrarium in an Aquarium

Alright, you’ve got your supplies. Now for the fun part! This is our complete how to make a terrarium in an aquarium guide. Take your time with each step, and enjoy the process.

  1. Plan and Design Your Layout: Before you add a single rock, sketch out your idea. Decide on your land-to-water ratio (a 50/50 or 60/40 split is a great starting point). Where will your “shoreline” be? Will you have a waterfall? A good plan saves a lot of headaches.
  2. Install the Hardscape and Divider: Now, build your structure. Securely place your rocks, wood, or silicone your divider into the clean, dry tank. If using silicone, let it cure for at least 48 hours before adding anything else. Safety first!
  3. Add Your Substrate Layers: Carefully add the false bottom (LECA/lava rock) and mesh screen to the land side. Then, add your chosen substrates to both the land and water sections. Now is a great time to shape and sculpt your terrain.
  4. Install Your Equipment: Place your heater in the water section and position your filter. If you’re creating a waterfall, run the filter’s output tubing to the highest point of your landmass before hiding it with rocks or moss.
  5. Plant the Terrestrial Section: Gently mist the land substrate to make it damp. Now, add your terrestrial plants! Start with larger plants in the back and smaller ones in the front to create a sense of depth. This is a chance to get really creative.
  6. Add Water and Plant the Aquatic Section: This is a key moment! To avoid messing up your aquascape, place a plastic bag or a small bowl in the water section and pour the dechlorinated water onto it. This disperses the flow. Once filled, you can add your aquatic plants.
  7. Cycle Your Tank: This step is non-negotiable if you plan to add animals. Your paludarium needs to go through the nitrogen cycle just like a regular aquarium. This process establishes beneficial bacteria to break down waste. It can take 4-8 weeks, so be patient. Your future inhabitants will thank you.

Choosing Your Inhabitants: Plants and Animals for Your Paludarium

Choosing the right residents is key to a healthy, thriving ecosystem. You need plants that love humidity and animals that are suited for this unique environment.

Best Terrestrial & Marginal Plants

The land portion of your paludarium will be very humid, so choose plants that love that environment. Great choices include:

  • Mosses: Java Moss, Sphagnum Moss, and Sheet Moss add a lush, aged look.
  • Ferns: Maidenhair Fern and Bird’s Nest Fern do wonderfully.
  • Vining Plants: Pothos and Creeping Fig are great for trailing down your hardscape. You can even let the roots of Pothos grow into the water—they are fantastic at absorbing nitrates!
  • Anubias and Bucephalandra: These classic aquarium plants can also be grown “emersed,” meaning their roots are in the water but their leaves are in the air.

Ideal Aquatic Plants

For the water section, you can use many aquarium favorites:

  • Low-Light Stars: Java Fern, Anubias, and Cryptocoryne species are hardy and don’t require intense light.
  • Floating Plants: Red Root Floaters, Frogbit, or Salvinia add surface cover and help control algae.

Animal Stocking Options

Once your tank is fully cycled, you can add some life! Remember to research the specific needs of any animal you consider.

  • Aquatic Life: Small, peaceful fish like Chili Rasboras, Ember Tetras, or Endler’s Livebearers are perfect. Neocaridina shrimp and various snail species add life and act as a cleanup crew.
  • Semi-Aquatic Life: For a more advanced setup, Vampire Crabs are a popular and fascinating choice. They require both land and water access. Certain amphibians like Fire-Bellied Toads can also work, but they require a very secure lid and specialized care.

Long-Term Success: Your Paludarium Care Guide

Your beautiful creation is complete! Now what? Following this simple how to make a terrarium in an aquarium care guide will ensure it stays healthy and beautiful.

Maintaining Humidity and Airflow

You need high humidity for your terrestrial plants, which a lid will help maintain. However, you also need some ventilation to prevent stagnant air and mold. A glass lid that leaves a small gap or has ventilation holes is ideal. Misting the land area with a spray bottle every day or two will also help.

Lighting and Water Changes

Keep your lights on a timer for 8-10 hours a day to provide a consistent schedule for your plants. Perform a 25% water change every week, just like a standard aquarium. Use a gravel vacuum to clean the aquatic substrate and simply refill with fresh, dechlorinated water.

Pruning and Plant Care

Your plants will grow! Don’t be afraid to prune back both terrestrial and aquatic plants to maintain your desired shape and prevent them from overcrowding each other. This is part of the fun of having a living work of art.

Avoiding Common Problems with How to Make a Terrarium in an Aquarium

Every hobby has its challenges. Here are some of the most common problems with how to make a terrarium in an aquarium and how to easily solve them.

  • The Problem: Mold or Fungus on Land. This is usually caused by a lack of airflow.

    The Solution: Ensure your lid has some ventilation. You can also add a “bioactive cleanup crew” of springtails and isopods to your land substrate. They will happily eat mold and waste, contributing to an amazing eco-friendly how to make a terrarium in an aquarium setup.
  • The Problem: The Land Area is Waterlogged. Plant roots are rotting and the soil is mud.

    The Solution: This means your drainage layer (false bottom) isn’t working correctly. When building, make sure your mesh barrier is secure and your soil level is well above the water line.
  • The Problem: My Animals Escaped!

    The Solution: A tight-fitting, secure lid is absolutely non-negotiable for any paludarium housing semi-aquatic animals like crabs or frogs. No exceptions!

Frequently Asked Questions About How to Make a Terrarium in an Aquarium

Can I convert my existing fish tank into a paludarium?

Absolutely! As long as the tank is in good condition, you can definitely convert it. You’ll just need to temporarily re-home your fish while you do the construction, then cycle the tank again before reintroducing them.

Do I need a filter for the water section?

Yes, I highly recommend it. While plants provide some filtration, a mechanical filter is essential for keeping the water clear, oxygenated, and safe for any aquatic inhabitants. It also provides crucial water movement.

What’s the best way to create a waterfall feature?

The easiest way is to use a small submersible pump or the output from a canister filter. Run vinyl tubing from the pump/filter outlet up to the highest point of your land area, hiding it behind rocks or wood. Let the water cascade down the hardscape back into the water section.

How do I keep the glass from fogging up?

A little bit of fog is normal due to the high humidity. You can minimize it by ensuring there is some ventilation. Installing a tiny, computer-style fan to blow air across the front glass can also work wonders for keeping your view crystal clear.

Your Two-in-One World Awaits

Building a paludarium is one of the most rewarding projects in the entire aquarium hobby. It challenges your creativity and results in a truly unique, living ecosystem that is more than the sum of its parts.

You’re not just keeping fish or growing plants; you’re creating a miniature shoreline, a tiny piece of a vibrant, thriving world right in your own home. We’ve covered all the tips and best practices, and now you have the knowledge to succeed.

So go ahead—start sketching your design. Your stunning land-and-water masterpiece is waiting. Have fun, embrace the process, and enjoy your own personal slice of nature!

Howard Parker
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