Can You Put Hot Wheels in a Fish Tank? (Will It Hurt?)

Hot Wheels are an incredibly popular toy that has been around for decades. If you were to go into virtually any house in the USA you would likely find at least one Hot Wheels car. 

Another thing that many people have is fish tanks as fish are super easy to take care of and they are often the first pet that people get. 

Since both Hot Wheels and fish tanks are incredibly popular there are many people who want to decorate the inside of their fish tank with their old Hot Wheel cars… but should they? 

You should never put your Hot Wheels cars inside of a fish tank as the paint and metals which the Hot Wheels are made of are toxic to fish and will also endanger the tank’s ecosystem. 

Decorations for your fish tank should be made of hazard-free materials, or only the ones that are labeled as aquarium ornaments. 

The water inside of your fish tank is sensitive and prone to rapid change so a small presence of toxic particles can easily disrupt its ecosystem and cause a devastating outcome for your fish’s health. 

To make sure an object is safe for your fish tank, wash and soak it first for 24 hours before submerging it into the aquarium even if it would be considered safe. 

However, a Hot Wheel car will never be safe as the paint will flake or the metal will rust thereby hitting your fish. 

Hot Wheels Materials That Are Harmful to Fish Tanks

There are a few different materials that Hot Wheels are made of that will pose a serious risk to your fish and even the water inside of your tank. 

Some of the materials that will cause problems are: 


Hot Wheels uses enamel paint to add colors to their cars. Enamel paint may not be directly harmful to fish, but it can dangerously threaten the biosphere thriving in the tank which would hurt them long term. 

In just a couple of days after you submerge the cars into the water, the enamel paint will start to bleed off into the tank’s water.   

It will soon change the color of the water as the paint continues to peel/leak. 

Toy cars losing their colors makes putting them inside any fish tank a bad idea and one that will be harmful long term. 


ZAMAC is the main substance that comprises the metal used for most Hot Wheels cars. The four metals making up ZAMAC are Zinc, Aluminum, Magnesium, and Copper. 

The rest of the materials will be fine inside of a fish tank, but Aluminum and Zinc are quite dangerous for the fish. It can bring them serious breathing problems as these minerals land in their gills. 

Apart from their direct effect on fish, the oxide from Zinc and Aluminum will also develop rust as they stay in the tank for a long time. 

The rusty parts of the cars will begin to shake loose and their metal flakes will begin to take over the tank. 

Can You Put Hot Wheels in Water?

Hot Wheels can withstand any weather, heat, and water and some models are even designed to be waterproof specifically. 

This feature makes kids more excited to play with Hot Wheels cars, but it turns out, nothing is made exactly perfect.

Although Hot Wheels cars can be submerged in water, the metal will eventually develop rust and can still be a potential risk if submerged for a while. 

The manufacturer experimented with the toys and unfortunately, the rust took over the water in just 5 months of them being continuously submerged. 

Decorations That Are Safe For Fish Tanks

Now that you know that Hot Wheels are not safe decorations for your fish tank let’s look at what decorations you can use inside of your tank without any problems. 


Rocks are organic material that are perfect for your fish tank. Many people are fond of adding large rocks to their tank as they are flexible and you can add as many or few as you like. 

However, you have to choose rocks that are hard and non-porous to avoid excessive calcium and other materials building up in your water. 

Softer rocks such as limestone and sandstone are more likely to leach minerals into your tank. 

Treated Wood

Normal wood is full of substances like tannins, which can affect the pH level and the hardness of the tank water. This means wood can dissolve the mineral count. 

Thus, fish keepers recommend only using treated wood if you want to add aesthetic touches to your aquarium. Treated wood is safe to put inside the tank since it is already processed as tannin-free. 

It is much better to purchase a set of ready-made wooden decorations than homemade ones to ensure the safety of your fish long term. 

Clay Pots

Treated and carefully made of safe materials, clay pots are another ideal option to spice up the decorations for your fish tank. These pots are kiln fired, treated, and non-toxic. 

For standalone decorations, caves, and tunnels, clay pots are a perfect fit to complement the overall design. 

Make sure the holes in the structures are large enough for any fish in your tank to pass through freely. 

Also, you might want to check for sharp edges around the clay pots before submerging them into the water to avoid cutting the fish that are in your tank of them swim through them or into them. 


If you have a green thumb and are also a fish lover at the same time, you can also add some plants to the fish tank. 

However, if your plants are not naturally aquatic, they will likely attract bugs and develop diseases underwater. 

You should also consider putting non-toxic plastic plants instead to achieve the design you want for your fish tank without any upkeep of real plants. 

Just glue the synthetic plants on to the rocks or attach them to the crevices of the pots. 

Ceramic Mugs

Ceramic mugs might not be attractive fish tank ornaments for some, but if you are a little creative in designing your tank, they can be positioned sideways and make a cave-like structure in the water. 

Experts suggest using only food-grade ceramic mugs however for your tank as the other type could give off poisonous chemicals into the water and eventually kill the fish. 

If they are good to eat off of, then there will be fewer chances of the ceramic mugs contaminating your tank. 

Other Things That Shouldn’t Go In Fish Tanks

Anything Degradable 

Objects that degrade easily are not good for your fish tank. It can alter the water which in turn can harm your fish or even end up killing them. 

Degradable items can release chemicals and toxins into the water, which is very harmful for the fishes and any vegetation that is in the tank. 

Anything Consumable

There should be no other consumable particles inside the tank aside from the food for the fish. Your pets will like to explore the objects inside your tank and they will also bite and chew a lot. 

Small rocks and plastic toys that can be easily torn may entice the fish to chew off the parts and eat them which can of course harm them. 

Anything Sharp

Glass and other decorations with sharp edges are a no-no in fish tanks. Such pieces could cut your fish and lead to infection. 

Check all of the aquarium toys or ornaments before purchasing or submerging them into the tank to make sure they aren’t sharp. 


Putting Hot Wheel cars inside a fish tank will ultimately be no good — both for the toys and the fish. 

When cars are soaked for too long, their paint colors can become distorted and the paint leaching into the water is harmful to the ecosystem and fish inside the tank as well. 

Ultimately, just don’t put your Hot Wheels into your fish tank. 

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