14 Fish Tank Decoration Ideas With Up-cycled Items

Get ready for a splash of fun decorating your fish tank with stuff around the house — it's like unleashing your inner underwater artist!

Updated February 16, 2024
Goldfish in a fishbowl

You can buy the standard sunken ship or plastic undersea plants at any pet shop, but if you want to give your fish tank a unique look, shop for decorations around your own home. There are tons of great fish tank decorations using everyday items, from your kids' toys to the stuff in your china cabinet, but there are some safety concerns to be aware of during your search. Try some of the awesome options listed while being aware of how to keep your fish healthy and happy.

Lego Your Heart Out

Love that insanely awesome model of the Death Star? What about that replica of Hogwarts Castle that took you weeks to complete? Legos can be perfect aquarium decorations, as long as you have the space.

Fish tank with Lego set-up

You can set up entire Lego scenes in the tank if you feel like getting super creative. Take a stroll through the Lego website to see the sets that are available. Here are some really cool ideas:

Quick Tip

Thoroughly clean your Lego creations before using them and every time you clean out the tank.

Make an Underwater Lego Zoo

Use Lego animals and bricks to make a zoo for the fish to enjoy.

An Underwater Atlantis

With Aquaman 2 out, there's no better time to make your own underwater Atlantis out of Legos (P.S.: The movie is fantastic!). You can make ancient ruins, temples, and treasure chests. And, to add some extra spark, consider some super-neat mythical sea creatures.

Build a Fish House

Create a literal home for your fish by building a house and filling it with Lego furniture and appliances.

Make an Undersea Universe

Dive into a splash of fun by using a kaleidoscope of bright Lego bricks to build your very own coral reef! Jazz it up with sea plants, starfish, and a whole crew of Lego marine critters to bring your reef to life. It's like you have a real-life Minecraft fish tank!

Aquarium Under Construction

Make some Lego construction vehicles and set up Lego people to work on the construction inside the tank.

Need to Know

Lego has stringent safety standards about the plastics they use in their toy bricks, making them a good choice for putting in a fish tank. Avoid using glue with the blocks, as this can contaminate your fish's water. And be sure to only use the actual Lego brand. These safety standards don't apply to generic brands.

Write a Message in a Bottle

There's nothing quite as mysterious and interesting as a message in a bottle. You can add a floating bottle to your fish tank with a few things you have around the house. This idea will work in almost any size tank.

To keep your bottle floating upright, place a couple of marbles or another weight at the bottom to make it heavier than the top. Experiment with different weights since the balance will be different for every bottle.

Helpful Hack

For a fun gift, write a love note or special message on a piece of paper and put it in the bottle so the note shows through the glass.

An Underwater Bottle Terrarium

Inside clear bottles, arrange small aquatic plants or moss to create miniature underwater terrariums. They offer an aesthetic appeal and a unique twist to traditional plant setups.

Related: 6 Betta Tank Decor Ideas to Inspire Your Next Setup

An Old-World Appearance

Choose an antique bottle or other ornate, interesting-looking example to give the whole decoration a really old-world feel.

Add Pops of Color

Consider a colored glass bottle for a pop of red, green, or bright blue.

Need to Know

For a fun gift, write a love note or special message on a piece of paper and put it in the bottle so the note shows through the glass.

Tea for Two...Fish

If you have some pretty china you never use, why not set up a tea party inside the tank? You can use your favorite pattern or just something you inherited from Grandma. Either way, it's an adorable, totally unexpected choice for aquarium decor.

Quick Tip

Avoid delicate finishes that might flake off, like gold or silver leaf on the edges of cups or saucers.

Goldfish bowl tea set decor

Fancy Feelings

Put a lace tablecloth under the tank to create the fancy feeling from the outside.

Make a Luxurious Shipwreck

Tip one teacup on its side as if it has gradually settled to the ocean floor from a luxurious passenger ship.

Grab a Little Teapot

Place a whole teapot inside the tank, making sure there's plenty of room for the fish to swim in and out of it.

Have a Tea Party

Use a child's tea set for a miniature version of the tea party, making sure you have enough settings for each of your fish friends, of course.

Need to Know

Fishkeeping World notes that you should only use food-safe ceramics in your fish tank. Since your china cabinet is full of food-safe dishes, you should have plenty of options. 

"Fish" Everyone a Happy Holiday

The holidays are a great time to get creative with the decorations on your tank, especially if you have some extra holiday decor. You can do this for any holiday, from Halloween to Easter to Christmas.

Need to Know

Anything found around the house could introduce bacteria into the tank. Look into how to disinfect it properly before adding it. 

Fish tank with Christmas decorations

Make the Aquarium Ornamental for Christmas

Pick some plain, colored glass ornaments and remove the hanging hardware. Fill the ornaments with water and place them on the bottom of the tank.

Have Some Easter Fun

If you have food-safe holiday figurines, like glass Easter bunny-shaped salt and pepper shakers, put those in the tank.

Need to Know

Avoid anything painted or sharp, even if it makes a cute holiday decoration. Similarly, consumable items are a bad idea. 

Must-Know Safety for Fish Tank Decorations

If these ideas have sparked your creative side and you plan to wander your house looking for more, check out these tips first:

Beware of Chemicals

Make sure to use items that are safe and won't release any chemicals into the water. Steer clear of anything with paint, varnish, metal, or coatings that you're not sure about.

Cleaning Thoroughly

Clean all decorations thoroughly with hot water. Avoid soaps or detergents, as they can leave harmful residues. For tougher cleaning, use a mild bleach solution (10% bleach) and rinse thoroughly multiple times. Allow it to dry, then rinse once more to ensure all the residue is gone. 

Teenage girl cleaning a home aquarium

Steer Clear of Metal

Metals can corrode over time in water, releasing harmful substances. Stick to glass, ceramic, or plastic items that are known to be aquarium-safe.

Be Careful With the Size

Ensure the decoration is appropriately sized for your tank and won’t topple over or trap the fish. Heavier items should be placed directly on the bottom of the tank, not on a substrate that could shift.

Decor Ideas for Your Fish to Explore

Creatively decorating your aquarium doesn't have to break the bank. Look around your house to discover some unique decor items your fish will love to explore, and visitors will enjoy checking out. Before placing any items in your tank, do a little research to make sure they're safe, especially if they aren't listed above.

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14 Fish Tank Decoration Ideas With Up-cycled Items