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Can You Put Metal Objects In A Fish Tank|10 Tips You Must Know

Decorating an aquarium is truly an exciting experience. It is where your creativity arises, and ideas float all over your mind. Whatever you put in your aquarium, you will go fine with the cute decorations available at the pet store. But, while decorating the tank, many fish keepers get the idea of putting metal objects in their fish tanks. Why? Because they like the shiny, beautiful look of metal. With lighting, water will reflect a more lustrous look in metal. But, Can you put metal objects in an aquarium?

Put Metal Objects In A Fish Tank

Can You Put Metal Objects In A Fish Tank

Although metal enhances the look of the tank, you cannot put metal objects in fish tanks. Metals like copper, brass, bronze, carbon steel, and iron corrode and oxidize in time. The new compounds (rust) they create while oxidizing are toxic for fish. There are exceptions, however. Very few metals are considered safe for use in fish tanks as they don’t corrode, or the oxide they create is non-toxic.

What Metal Objects Safe for Fish Tank

Stainless steel and Titanium are considered safe metals for your fish tank. But, the cost of those metals is high that a common aquarist will ignore them.

Can I Put Stainless Steel in My Fish Tank?

Yes. You can put stainless steel in your fish tank. What makes metal not suitable for a fish tank is its corrosion. Every metal corrodes in a matter of time; oxides form on the surface and will poison your fish and entire aquarium. Stainless steel takes a long time to rust. Therefore using them for short periods is safe.

Put Metal Objects In A Fish Tank

Is Aluminium Safe for Fish?

Not at all. Aluminum is more dangerous for fish in the tank. Aluminum produces CO2 during oxidation, which is toxic for fish. The fish may die due to a combination of ionoregulatory, osmoregulatory and respiratory dysfunction (National Library of Medicine) because of acute aluminum toxicity.

Can You Put Aluminium Foil in a Fish Tank?

Absolutely not. Although aluminum foil or tin foil includes a tiny amount of aluminum (aluminum layer thickness is less than 0.2mm according to Wikipedia ), that small amount can be toxic for fish. If you put aluminum foil in a fish tank, the foil will eventually leech metals into the water, which is not suitable for the fish.

Is Titanium Metal Safe for Fish?

Yes. Titanium by far is the safest metal to use in an aquarium. Titanium is an inert element. It doesn’t corrode. The oxidized form of Titanium, Titanium Dioxide, is exceptionally unreactive. However, they are going to be quite expensive so you would instead stick with plastic decorations.

How to get Titanium for Aquarium Cheap?

Titanium is not a cheap metal you can buy anywhere. But, there’s a cheap way to buy Titanium. You can buy titanium Bike-Wheel spoke for about 2 to 3 bucks a piece at your local bike shop. You can then bend that to a shape pretty quickly.

Can I Put Gold in Fish Tank? Is it Safe?

Gold is one of the least reactive metals in the periodic table. Gold doesn’t react with oxygen, so it never rusts or corrodes. They don’t react with air, water, alkalis, and all acids except aqua regia. Now, keep in mind that we are talking about 24K pure gold, not gold sold in stores. Pure gold is so soft that it bends and warps easily.

To get a hard metal out of gold, we mix gold with other metals like copper and alloy. The metals mixed with gold may be reactive to water which makes it not safe for fish tanks. But, if you can find 24K gold, you are free to put them into your tank. But, I doubt neither you find them nor keep them in your tank.

Also, Read Aquascaping Advanced Guide-Learn Professional Aquascaping

How to Reduce Metal Decay in Metals in Tank

For any reason, if you have to put metal into the tank, you should prevent them from decaying. It’s not the metal that is toxic for the fish. It’s the oxide that forms on them. So, if you take measures to prevent oxidation, you can safely use metal in an aquarium.

The metal can be powder coated or anodized to reduce corrosion. You can also cover them with a lubricant or a soft sealer like Vaseline to seal the metal. Sealed metal using the above steps is considered safe for a fish tank.


You may find fish creating colonies out of metal objects like tins and soda cans in the wild like lakes and sea. Are they non-toxic for those fish? No. They are toxic for any fish but, the water volume of lakes and seas is huge and small amounts of metals can’t do much to the whole system.

Therefore, the fish that live in the lake aren’t affected by the metal rust. On the other hand, human-made fish tanks contain small amounts of water volume, mostly about 200 gallons. With that much water quantity, even one metal object can be fatal to the fish that live in the tank.

Titanium and Stainless Steel are the only safe metals known that is suitable for fish tank. Every metal corrodes in a matter of time, including Titanium and stainless steel. The only safe point of those two metals is that they take much longer to corrode.

We might give up using that metal object to decorate our tank before it starts to corrode. Pure gold is considered safe for fish tanks, given that they are not mixed up with any other metal. But, pure gold is not a practical choice as you cannot find pure gold easily in stores.

You can put many other objects into your aquarium, like glass pebbles, fake and live plants, sand, stones, and gravel. Most of the time, lesser decorations are better as your fish might not have enough space to explore in your tank. Fish prefer water more. So, keep your decorations minimum and avoid using metal objects for decoration, except for Titanium and stainless steel.

Also see Put Lucky Bamboo In Aquarium? Is Bamboo Safe For Fish?

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About Dr.Chamika

Hello, I'm Dr. Chamika. I am a Researcher in Water quality, Aquatic organisms, and Environmental chemistry. I am a passionate fish keeper, with10 years of experience. My mission is to help other aquarists experience the joy of fish keeping.