# Aquarium Decorations – Safe or Toxic?



## Aus

Bombalurina suggested I make a post about choosing safe rocks to use in an aquarium, as I mentioned in another thread that some minerals are really toxic (I collect minerals as a hobby). While I’m at it, I thought I’d include other decorations as well, such as plastic and ceramic items. 

Decorative items sold in pet and aquarium stores that are marked as being specifically for aquarium use are usually very safe. But not all objects you may find around the house or in nature are okay in the fish tank, as some will leach out toxins that will, sooner or later, become toxic to your fish. 

So how can you make sure to pick safe items? One way is to use nothing that isn’t from a store and marked specifically for aquarium use. But you can also do a little homework about the likelihood of toxicity in other items, and make good choices based on that.

The following list isn’t 100% comprehensive, but might be useful in helping you choose safe decorations. 

Basic common sense: *if in doubt, don’t put it in your tank.* It’s better to be safe than sorry!



*Plastic*

Plastic is one of the most-used materials in fish keeping. Many plastics are completely safe- the acrylic used in fish tanks, for example, and the materials used in plastic plants and other aquarium decorations. Some plastics, however, will degrade in water or release toxins when heated even slightly. 

- A general rule to keep in mind is this: *if something smells like plastic, don’t use it.*

- Soak the item in hot water. If it has a plastic smell after that, don’t use it. If the plastic feels slimy in the water or goes brittle when dried out again, don’t use it.

Really, any plastic decoration that isn’t made for aquariums should be viewed as risky. It might be fine – but then again, it might not. 


*Glass*

Most smooth glass items are fine. There’s a couple of exceptions I’m aware of:

- Lead crystal – because… it contains lead. :shock:
- Antique glass – because lead was very commonly an ingredient in glass decorations.
- Painted glass – glass paint can be extremely toxic.
- Unsealed mirrors – that stuff on the back of a mirror which makes the glass reflective is often really toxic. *Don’t stick mirrors not marked specifically for aquarium use in your tank. 
*

*Ceramics*

Basically, any item that cannot be used for human food or drink (like raku pottery, which contains a LOT of heavy metals such as copper and lead) should never be used in your fish tank.

Unfired pottery like terra cotta is very porous, so should never be used if there’s a chance it has been exposed to detergents, garden sprays and other toxic chemicals, or used for plants (in case of fertilisers). 


Brand new terra cotta can affect ph levels, so it’s best to ‘age’ your pots a while by soaking them in a bucket of tap water before use for at least 24 hours, and then testing the ph.

*Avoid ALL metallic glazes.* They can be horribly toxic.

Bright red, blue and yellow glazes on non-food grade ornaments that are not specifically made for aquariums MAY be very toxic, and MAY leach poisons into the water. I’d personally not risk it.


*Wood*

The subject of wood in tanks really needs a whole thread to itself, and there’s been a lot of good advice given on this forum already, so I’ll keep it brief:

Wood marked for aquarium use at the LFS is often quite expensive – but this is because it has been aged, pre-soaked, cleaned and treated to make it safe for use. Common woods for sale at LFS’s are Mopani, Bogwood, Redmoor root, Mangrove root and clean driftwood. 

Be very careful about using wood you have found outside. 

Wood is very porous and absorbs environmental toxins and poison sprays easily, so don’t use wood found in the garden unless you are very sure nobody’s ever used herbicides or pesticides on that land or nearby as sprays can drift a long way. 

Some wood contains sap that can be extremely toxic in general, especially when the wood is green. To be safe, never add any unidentified wood to your tank. 

*Never use green wood* (cut less than a year, or better, two years ago) in your tank – some wood that is safe when completely dry is not safe when green, or even for several years after it’s been cut. It may contain sugars and starches that will upset your tank’s chemistry, or toxic sap. 


*Shells and Coral*

These aren’t recommended for use in freshwater tanks, because they contain calcium which dissolves in water and can dramatically increase the ph and hardness levels. 


*Rocks*

*Not every rock is safe* *for aquarium use*, *especially in water with low ph*.

Aside from the danger of sharp or jagged edges and rough surfaces, some rocks contain high levels of toxic minerals and elements (like lead and arsenic) that can leach out into the water and will quickly poison your fish.

Low ph makes water soft and acidic, which frees otherwise inert (safely 'locked up') minerals and elements from the rock so they leach into the water, making it toxic. 

Some minerals (like fluorite and calcite) will dissolve in water and affect your water chemistry. 

Speaking VERY generally, the safest rocks:

- *Are extremely hard* and will not go soft even after a month of being soaked in water, and do not shed a lot of particles or scratch badly when scrubbed with a scourer.
- *Do NOT have any metallic particles* in them, something you sometimes can’t tell without a microscope…


_*Generally regarded as safe:*_

- Basalt
- Clear and white quartz (don’t use spiky crystal clusters, for obvious reasons, and avoid any quartz that contains glittery fool’s gold, which can be very toxic).
- Igneous rocks (Obsidian, Granite & Gneiss – watch out for sharp bits, though)
- Petrified wood
- Very hard, smooth, water-worn ‘river rocks’ (must be boiled before use, don’t oven-heat though as some will explode in dry heat).


_*Cautionary, best avoided:*_

- Shale and slate can contain pyrites (poisonous metals) and sometimes fossil oil residue. I’d avoid collecting them for aquarium use, just in case. 

- Limestone, dolomite, marble, sandstone, siltstone, calcite, fluorite and other ‘soft’ and ‘brittle’ rocks contain minerals that will dissolve in freshwater tanks and quite seriously mess up your water chemistry.

- Brightly coloured minerals and crystals you might find at a new age store, gift store or market - like Turquoise, Malachite and Azurite, which have very high levels of copper and/or aluminium, and Lapis lazuli which very often contains toxic pyrites. 

_*AVOID at all costs:*_

- Any ore (metal bearing rock), and any metallic or ‘glittery’ minerals - these will almost certainly poison your fish.


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## wystearya

Lead Crystal leaks lead..? Then how can they sell them as drinking glasses, like for wine..?

I'm just curious! >> I think this is a great topic, and I am glad to have the information. <3


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## Aus

Lead crystal -can- be dangerous if acidic stuff (..like wine..) is stored in it for long periods, as stated in this article:

http://seattletimes.nwsource.com/html/foodwine/2004260515_wineqanda05.html

It's also recommended that pregnant women and children avoid lead glassware, so I'm pretty sure it shouldn't go in the fish tank, just in case.

From another article:

http://www.thenibble.com/reviews/main/wine/lead-crystal.asp

"Preliminary tests have shown that, over time, significant amounts of lead can migrate from lead crystal containers into liquids stored in them. 

One research team measured the amount of lead migration in Port wine that was stored in lead crystal decanters. After two days, lead levels were 89 micrograms; after four months, lead levels were between 2,000 and 5,000 micrograms.
White wine doubled its lead content within an hour of storage, and tripled it within four hours.
Brandy stored in lead crystal for five years had lead levels around 20,000 micrograms.
Any liquid can leach lead from crystal just as effectively as wine and other alcoholic beverages.
 To put these numbers into perspective, the EPA’s lead standard for drinking water is 50 micrograms per liter."


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## wystearya

Learn something new every day! 

Thanks for the link.


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## ANHEL123

Thank for information it good to know.

 Just want to say something about plants. I was using plants at the beginning about 4.5 years ago when i just got my very first betta. I used to buy them in the pet store. Then i stopped because i saw that they kept them in the tank with fish. So i was afraid that they carry disease. 
Now i found out that you need to quarantine the plants for 2-3 weeks before you use them , because they are carry disease.

I don't buy any plants from pet store. I am using spider plant which very easy to take care of and they stay longer than other plants. My mom has them and my friend has them. I think a lot of people familiar with spider plants. They can vary in color, size, shape of the lives. My bettas love them. I wish everyone know that and don't spend money on pet store plants which can carry disease and kill your fish.

Rocks i always buy just natural rocks in the pet store. I try to avoid colored rocks. Also i bought a few times river rocks. Black and white rocks i never had problems. But river rocks a little bit expansive. Tell you the truth i brought rocks from the shore. When i am going on vocation i always bring rocks. But i soak them in the water before i am using them.


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## Oldfishlady

Awesome job......great information.....

Please, please be careful boiling or baking rocks.....while the odds of an explosion is rare....it can happen and why take the chance when you have other safer methods....if you do opt to boil the rock....do it outside away from your house.....better safe than sorry......


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## ANHEL123

So any disease that fish had we can sterilize the gravel and use it for another fish?

 I agree why take a chance if we can boil them. For how long we should boil them?


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## DoberMom

Wait, so no ceramic figurines that I can find online should go in my tank??  is there no way to make them safe?


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## Wolfie305

Is something like a flower pot okay to put in freshwater tanks?


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## Aus

DoberMom said:


> Wait, so no ceramic figurines that I can find online should go in my tank??  is there no way to make them safe?


I'm not an expert on that, but I do know some glazes will dissolve and release harmful stuff into water, like raku pots which contain arsenic and lead in the glaze. 

From the research I've done, pretty much any food-grade ceramics are safe, as nobody wants lead or other poisons in their food, and they are generally fired hard so the clay won't dissolve, etc. 

Not sure about ornaments, I have no information on what might be safe and what might not as far as they go. I do know a lot of antique glazes used some pretty hardcore poisonous minerals for colouring, etc. 

I think some more research into this is warranted. I'll see what I can do there, or maybe there's somebody here with a degree in pottery or something who could offer advice on possible toxins.


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## Aus

Oldfishlady said:


> Awesome job......great information.....
> 
> Please, please be careful boiling or baking rocks.....while the odds of an explosion is rare....it can happen and why take the chance when you have other safer methods....if you do opt to boil the rock....do it outside away from your house.....better safe than sorry......



Thank you. 

And thanks for that additional advice. I would never use dry heat on rocks, as I have seen many an explosion on camping trips when there's been a river rock used to build the fire pit. Very dangerous indeed! 

As for boiling, I have never seen an explosion from that, but I trust your experience -and would perhaps not boil the rock, but rinse several times in near-boiling water as an alternative. Not many pathogens will survive repeat exposure to very hot water. 

Another thing to look out for there is sudden temperature changes - never dunk a boiling hot rock in cold water! It'll crack or explode and the shards can be razor sharp.


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## Aus

ANHEL123 said:


> So any disease that fish had we can sterilize the gravel and use it for another fish?
> 
> I agree why take a chance if we can boil them. For how long we should boil them?


I believe one method is using a weak bleach solution to rinse the gravel and then rinsing VERY thoroughly afterwards (many times) and leaving it spread out on some plastic to thoroughly dry in the sun (sunlight degrades the nasty stuff in bleach). 

I don't think anything needs to be boiled for a long time. A few minutes, let it cool off the boil (to avoid cracking) and then rinse and rinse again with cold water.


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## Aus

Wolfie305 said:


> Is something like a flower pot okay to put in freshwater tanks?


A lot of folks use terracotta pots, but there's a few safety measures mentioned elsewhere here - first being the hole in the bottom, which fish have gotten stuck in. Best to plug that up with a sponge or some other aquarium-safe method. 

Also, brand new terracotta can sometimes affect ph levels dramatically so best to 'age' it a while by soaking it a few days and leaving it to dry somewhere it won't absorb toxins. Then soak again, and test the ph levels against your regular tapwater ph. Rinse, repeat until it doesn't change the ph anymore. 

I'd avoid painted pots, for the same reason I'd avoid painted glass - goodness knows what's in the paint..


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## ANHEL123

Thank you for information 

About disinfection with bleach i would not recommend to bleach rocks, plants , anything porous or that can't stand the bleach...

For the tanks 10% of the bleach you can use to disinfect the tank. Let it stay at least 30 min rinse very well wipe, rinse let it sit in sunlight for a few days to neutralize the bleach . Rinse again. 

Also i want to say something else about plants that I already wrote before. When you buy hardy plan put them in tap water NO conditioner. now, wimpy plants may/will die,so be warned! I’ve had to with sword, wisteria and java fern…wisteria died. the others lived If you quarantine for 2-3 or more weeks,the diseae will die off. The thing about ich,velvet,etc,is it needs a host…no host ,it eventually dies.

You can boile fake plants and ornaments and air dried after that.

But I am not sure about fungus. I don’t think you can reuse plants from fish that had fungus….


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## Leeniex

I bought a polyresin cave that I rinsed in hot water and placed in one of my tanks. The next day the tank was very cloudy, so I took it out. Won't use that material any more.


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## registereduser

what do you think about these rocks? walmart $4 a bag.

http://akasha-us.com/about.htm


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## ANHEL123

I love these river rocks. It actually the same rocks that i have in every tank. I just was talking to someone and recommending them. I usually buy them from pet store. Those rocks very easy to rinse too. Well i am doing 50% and 100% water changes for my bettas. As long as i have my bettas i have those stones...I have a few 4 years old bettas.


 Now I am want to warn you. One time i bought them in the Target. The stones were in the see through container. It was river stones. I put them in the tank and in a few days my water got blurry. And it was not bacteria bloom. At first I couldn’t understand what happened …I have my fish for so long and I do the same care …so it appeared that those stones have some kind of layer of something on them..it clear so you can’t see it but if you scratch with your nail it will come off . You don’t need to be scared to use it. Those still didn’t kill my fish. My fish was all fine. But I didn’t use the rocks though..Just scratch the stones and see it it has something on it. Or put in water in the clear glass and see if water is blurry. By picture I can tell probably it the same rocks that I am using right now.


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## registereduser

:thankyou:


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## LugiaChan

"Now i found out that you need to quarantine the plants for 2-3 weeks before you use them , because they are carry disease."

 I am getting new plants for my tank, could you help me and point out where/what is some information on quarantine-ing for plants? Thank you 

As a side note: I think we should sticky a thread like this. Maybe also some people can add things that we can safely use for tanks because there's not a whole lot of selections due to toxic chemicals, i'm wondering about styrofoam or maybe *anything* else at all that would be great to use.


(Chemistry class!)


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## brettwashere

Hey I picked up a mopani root from the store and after more than a week soaking it still stains the tanks water. Any suggestions or is this ok? Also I put three terra cotta pots into my tank. Didn't really consider if the could be toxic as I have see terra cotta in tanks before. Any insight on terra cotta? Thanks


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## Aus

The terracotta isn't toxic - it apparently just sometimes raises the ph when brand new, and is perfectly fine after being aged a little while in water. The tannins in the mopani root are actually good for bettas - there's lots of tannins in their natural environment and tannins lower ph, so the root and pots just might level each other out, lol.


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## Sena Hansler

you can reuse stuff that had fungus.... live plants, not sure. But anything that has come in contact with fungus, it's the same....most bacterias cannot survive boiling... hence why we use hot water for dishes, and cook our meat ;-) 

Quarantine all live plants. This IS a must. There has been so many cases of "I got a new plant and now my betta is dying" because columnaris, ich, or some other disease clung onto that plant. My one plant got black hair algae that snagged my one girl!!

Styrofoam is safe. You can use it to make a background, and there are some paints and cement you can use to texture it, and make it look awesome. Styrofoam cups, are also used for some breeders for the male to make a covered nest ;-)

Marbles, that are not broken, and are completely smooth, can safely be used in aquariums after being sanitized. Surprisingly, lego can be used too - asides from the ones with stickers, or painted on faces. 

Things like green army men, are not recommended...and anyways, you can buy some MADE for aquariums =D (totally want them xD)


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## ANHEL123

Sena Hansler said:


> you can reuse stuff that had fungus.... live plants, not sure. But anything that has come in contact with fungus, it's the same....most bacterias cannot survive boiling... hence why we use hot water for dishes, and cook our meat ;-)
> 
> Quarantine all live plants. This IS a must. There has been so many cases of "I got a new plant and now my betta is dying" because columnaris, ich, or some other disease clung onto that plant. My one plant got black hair algae that snagged my one girl!!
> 
> Styrofoam is safe. You can use it to make a background, and there are some paints and cement you can use to texture it, and make it look awesome. Styrofoam cups, are also used for some breeders for the male to make a covered nest ;-)
> 
> Marbles, that are not broken, and are completely smooth, can safely be used in aquariums after being sanitized. Surprisingly, lego can be used too - asides from the ones with stickers, or painted on faces.
> 
> Things like green army men, are not recommended...and anyways, you can buy some MADE for aquariums =D (totally want them xD)


 
Just wrote it again...


When you buy hardy plan put them in tap water NO conditioner. now, wimpy plants may/will die,so be warned! I’ve had to with sword, wisteria and java fern…wisteria died. the others lived If you quarantine for 2-3 or more weeks,the diseae will die off. The thing about ich,velvet,etc,is it needs a host…no host ,it eventually dies.

You can boile fake plants and ornaments and air dried after that.


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## Sena Hansler

I noticed


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## swampdiamonds

This is a really old thread, but I'm a potter and want to restate that you shouldn't use decorative ceramic items in your tanks unless they were specifically made for aquariums. Commerically-produced food-safe objects are probably okay. However, purely decorative (non-functional) pottery is usually covered in what's called a low-fire glaze. These glazes are not food-safe, which means that metals and toxins can leach out into liquids. They can have chemical reactions, in other words. Food-safe glazes are usually fired to much higher temperatures, which means things are bonded more tightly and won't leach as much.​
Many, many glazes can leach when they come in contact with acidic foods and liquids, so that's also something to watch for.

And yes, red and metallic glazes should be avoided.

Unglazed ceramics will be safer (just like terracotta), but I would suggest making sure that the item has been fired to a high-fire temperature (or cone), since that burns out more of the organic and hazardous materials in the clay. Also, the lower the firing, the more porous the ceramic will be. The higher the temp, the more the clay particles will melt and fuse together.


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