Fish Tank Christmas Decorations: 15 Aquarium-Safe Picks (and What Never Goes in the Water)

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The best fish tank Christmas decorations are resin ornaments made for aquariums: they are sealed, they sink, they have no metal parts and they rinse clean. Our top pick is the SLOCME Aquarium Christmas Tree, a 6-inch resin tree that fits any tank from 10 gallons up. For a nano or betta tank, the 3-piece tree, Santa and snowman set is sized for small water, and the Ulifery snowman doubles as a betta cave. For a natural look, tie live Christmas moss to a branch of driftwood and grow your own underwater tree. Lights, tinsel and anything electric stay outside the glass.

When I was nine I took a painted plaster Santa from my mother’s Christmas village and dropped it into our living room aquarium. It looked perfect for about four days. Then the red coat started to flake, the water turned cloudy and my father lifted Santa out with the fish net, did a big water change and gave me the rule our family kept from then on: nothing goes in the tank unless it was made for a tank. I have kept fish for most of my life since, through a degree in marine biology, and every December the rule still holds. This guide covers the decorations that pass it, the ones that do not, and how to set up a Christmas tank without stressing the fish that live in it.

Fish tank Christmas decorations at a glance

Is it safe to put Christmas decorations in a fish tank?

Yes, if the decoration was made for aquariums. Aquarium ornaments are cast from resin or fired ceramic and sealed so the paint does not touch the water. Household Christmas decorations are not. Paint, glue, glitter and metal that are harmless on a shelf leach into water or break apart in it, and fish breathe that water through their gills all day.

Never put these in the tank:

• Tinsel, glitter and garland. Plastic film and glitter shed into the water, clog filter intakes and get swallowed.
• Glass tree ornaments. The caps and hangers are metal, the paint is not sealed for water and a broken ornament leaves sharp glass in the gravel.
• Anything metal. Steel rusts, and copper and zinc are toxic to fish and lethal to shrimp and snails even in small amounts. Jingle bells, wire ribbon and figurines with metal parts stay out.
• Plaster, painted ceramic and craft figurines. Plaster dissolves. Craft paint and glaze not rated for aquariums flake and leach.
• Fake snow, flocking and spray snow. Flocked trees and spray snow shed fibers and chemicals, and aerosol spray drifts into open-top tanks.
• Christmas tree branches, needles and wood. Pine and fir sap is toxic to fish, and commercial Christmas trees are often treated with pesticides. Even a fallen needle from a tree next to an open tank is worth fishing out.
• String lights. Holiday light strands are not waterproof. The only lights that go inside a tank are submersible aquarium lights sold for it.

Aquarium-made decorations still need a quick check before they go in. Run a pair of nylon tights over the surface: if the fabric snags, the edge is rough enough to tear a betta’s fins, so sand it smooth or skip it. Look at every opening. A hole should be either wide enough for your biggest fish to turn around inside, or too small for any fish to enter. Loaches, plecos and small catfish wedge themselves into narrow tunnels, and r/Aquariums has threads from keepers who had to break an ornament apart with pliers to free a stuck fish. Hollow ornaments also trap air, so check that yours sinks and stays put before you plant it in the gravel.

Best Christmas tree decorations for aquariums

A tree is the one decoration that reads as Christmas from across the room, and it is the easiest piece to place: put it toward the back third of the tank so the fish swim in front of it.

Best Santa and snowman aquarium decorations

Santa and snowman figures are the second piece most people add after a tree. Pick one large figure for a 20 gallon or bigger tank, or one small figure next to the tree in a 10 gallon. More than two or three holiday pieces in a small tank starts to look cluttered and leaves the fish less room.

Best Christmas decoration sets for small tanks

Nano tanks and betta tanks need small pieces. These sets are scaled for 3 to 10 gallons, where a 6-inch tree would take over the floor.

A natural Christmas look: moss, red plants and white sand

Not every Christmas tank needs a Santa. Many planted-tank keepers skip figurines and build the season out of plants: a moss “tree”, a few red plants against the green and a patch of white sand that reads as snow. These stay in the tank after January without looking like you forgot to take the decorations down.

Christmas backgrounds and lights

The safest decorations of all never touch the water. A background on the outside of the back glass and lights around the stand change the whole look of the tank with no risk to the fish.

For the fish keeper’s Christmas tree

The house tree can join in too. Fish ornaments are a common gift between fish keepers, and a good one costs less than most aquarium decorations.

How to decorate a fish tank for Christmas

1. Pick one theme and two or three pieces. A tree plus one figure looks festive. Five figures in a 10 gallon looks like a gift shop shelf and takes swimming space from the fish.
2. Check size against your tank. As a rule, keep any single ornament under a third of the tank’s height and leave open water across the front.
3. Inspect and rinse. Run the tights test over every surface, check openings, and rinse each piece under plain tap water while scrubbing with a soft brush. Do not use soap, dish detergent or bleach.
4. Add pieces during a water change. Your hands are already in the tank, and the fresh water dilutes any dust you missed.
5. Place them at the back and sides. Push bases into the substrate so they cannot tip. Leave hides near plants where shy fish already rest.
6. Decorate outside the glass. Add the background, then lights around the stand. Keep every plug below the tank level with a drip loop in the cord, and plug aquarium equipment into a GFCI outlet.
7. Watch the fish for a day. If a fish hides more than usual, stops eating or gets wedged in an ornament, take the new piece out.

Keeping your fish safe during the holidays

The decorations are the easy part. Most holiday problems in fish tanks come from what happens in the room around them.

• Keep the Christmas tree away from open tanks. Falling needles carry sap and possible pesticide residue. Leave a few feet between a real tree and the water, or keep a lid on the tank.
• No aerosols near the tank. Spray snow, air freshener, scented candles and cooking smoke all drift into the water through an open top or the air pump intake. Spray decorations in another room.
• Watch room temperature. A fireplace, a space heater or a door that opens to winter air all swing water temperature. Check the thermometer on party days.
• Put the fish food away during parties. Guests, and especially children, love to feed fish. One generous pinch from each visitor overfeeds the tank, and the uneaten food fouls the water by morning.
• Plan for travel. Most healthy adult fish handle three or four days without food. For longer trips, use an automatic feeder you have tested at home for a week first, or ask someone to feed small portions.

I learned the party rule the hard way. A friend’s six-year-old spent most of a holiday party at our tank, and every adult who passed handed her the food can. By the next morning the water was cloudy and smelled sour, and I spent December 26 doing water changes instead of eating leftovers. Since then the food can goes in a kitchen drawer whenever we have guests.

When to take the decorations down

Resin ornaments can stay in the tank as long as you like. Most keepers take them out in early January with the rest of the house decorations. Lift them out during a water change, scrub off algae with a soft brush and plain water, let them dry completely and store them in a bag away from the cleaning supplies. Throw out any piece where the paint has chipped through to bare resin or the finish has turned chalky. Next year, rinse them again before they go back in.

Live Christmas moss and red plants can stay all year. If you are setting up a new tank for the holidays, our What fish should I get? quiz matches fish to your tank size and experience, and the aquarium calculator works out volume and stocking. Betta keepers can also read our guide to the best filter for betta fish, since a gentle filter matters more to a betta than any decoration.

FAQ

Can you put Christmas decorations in a fish tank?

Yes, if the decoration is made for aquariums. Resin and ceramic aquarium ornaments are sealed and safe. Household Christmas decorations such as glass ornaments, tinsel, painted figurines and anything with metal parts are not safe in water.

Are resin Christmas decorations safe for fish?

Resin ornaments sold for aquariums are safe. The resin is inert once cured and the paint is sealed under a clear coat. Rinse new pieces in plain water, check for rough edges and remove any piece if its paint starts to chip or peel.

Can I put Christmas lights in my fish tank?

No. Holiday string lights are not waterproof and are not safe inside a tank. Use a submersible LED aquarium light if you want red or green light in the water, and keep string lights outside the tank with the plugs below tank level.

Do Christmas lights bother fish?

Steady lights outside the tank do not bother most fish. Flashing or fading lights and lights left on all night do. Keep the tank on its normal 8 to 10 hour light schedule with a dark period at night.

Can I put a real Christmas tree branch in my aquarium?

No. Pine, fir and spruce contain sap that is toxic to fish, and commercial Christmas trees are often treated with pesticides. Use live Christmas moss on driftwood for a real-plant tree instead.

What is Christmas moss?

Christmas moss, Vesicularia montagnei, is a live aquarium moss with layered triangular fronds that look like the branches of a fir tree. It grows slowly in low light and is safe with fish, shrimp and snails.

How do I clean aquarium decorations before putting them in?

Rinse them under plain tap water and scrub with a soft brush. Do not use soap, dish detergent or bleach, since residue harms fish. Add new pieces during a water change.

What Christmas decorations are good for a betta tank?

Small, smooth pieces with a hide: a hollow snowman cave or a small three-piece set suits a 5 gallon betta tank. Test every surface with nylon tights so nothing snags the betta’s fins, and avoid stiff plastic plants.

When should I take Christmas decorations out of my aquarium?

Whenever you like. Resin ornaments can stay in all year. Most keepers remove them in early January, scrub off algae with plain water and store them dry until next December.

Sources

• Wikipedia. Vesicularia montagnei.
• Buce Plant. Christmas Moss Tree.
• r/Aquariums. I got some of these from a Christmas tree lot, can I boil and then put them in a tank?
• r/Aquariums. Can Christmas tree wood go in a tank?
• r/Aquariums. Weather loach ornament injury.
• r/Aquariums. Need to get pleco out of ornament!
• r/Aquariums. Waiting for my underwater Christmas tree to grow.