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Decorating Your Fish Tank: Dos and Don'ts

Updated on January 25, 2016
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Marine Biologist. Aquarist. Capricorn. Lover of books, movies, music, animals, and all things Disney. Dreamer. Nerd.

Tips for how to safely decorate your fish tank.
Tips for how to safely decorate your fish tank.

Where to Begin?

You have your perfect tank, complete with all the bells and whistles of filtration. You have your water quality test kit ready. You have a list of fish you would like in your collection. So, how are you going to decorate your aquarium? Believe it or not, this is where a lot of people run into problems. Sometimes they get so excited about all the cute decorations at the pet store that they overcrowd the bottom of the tank. This is no good. Not only will this make doing tank maintenance harder (just think of trying to gravel wash all that), but it also it looks tacky. With that in mind, how do you pick out decorations for your tank? This is the time to be creative, as the sky is truly the limit.

Work From the Bottom up

The first step in decorating your fish tank is choosing which substrate to use to cover the bottom.
The first step in decorating your fish tank is choosing which substrate to use to cover the bottom.

The first thing you want to consider is what kind of substrate to use. There are many different options. Do you want a sandy bottom? What about small gravel, or large? You can even use small stones. Do you want to use glass pebbles? Do you want the tank to be colorful or more natural?

The most important thing to consider when choosing a substrate is your fish. Sometimes the type of fish you want will dictate what kinds of substrate you have to use. If you want fish like eels or knifefish, you need to have a sandy bottom. Eels will spend most of their time on the bottom, and if you have a rocky substrate, they will rub their bodies raw, which is bad for them. If you are considering a freshwater ray, then you need to have a large bottom with sand. They will bury themselves in the sand, which would be nearly impossible for them to do safely in a tank with gravel as the substrate. Sand will also give your tank more of a saltwater feel, which many people desire.

However, sand does have some downsides. If you plan on doing gravel washes, which you should strongly consider, sand can make them more annoying. Since the sand is smaller and lighter than gravel, it tends to travel higher up the tube. It also tends to end up in whatever you are using to collect your waste water. This means that you will need to replace sand more often than you would have to replace gravel.

Gravel and stones are popular choices for freshwater tanks. They create a natural look for the tank and they are easy to clean. They are a better alternative to colored glass pebbles which, however pretty, are not always the best choice for a large fish tank. Glass pebbles aren't necessarily bad for your fish, they simply do not provide as much surface area for good bacteria to colonize. You need good bacteria to keep the nitrogen levels in your tank in check. Glass pebbles over time will break down, as is natural, and gravel will erode as well. However, the glass pebbles will have sharper edges whereas the gravel will just become finer. Glass pebbles are pretty, but they are just for show. It would not be harmful to have a few of them scattered throughout the bottom of the tank, as they will add some color. Just be sure to change them out once they begin to show signs of wearing down.

You need to make sure that everything you put into your tank is properly rinsed—and that includes your substrate. Sometimes you need to rinse it a few times to get all of the dust and debris out.

Plants: Live or Fake?

Fake plants can lend your tank a splash of colors. If you are using live plants, make sure that they are a species that can be fully submerged in water.
Fake plants can lend your tank a splash of colors. If you are using live plants, make sure that they are a species that can be fully submerged in water.

Plants are a very popular decoration in many aquariums. Some people like them because they add color to the tank. Some add them because plants are found in many freshwater environments and can give the tank a more natural feel. If you go to the pet store, you will see a wide array of choices when it comes to aquarium plants.

The vast majority of home aquariums use plastic plants in place of live ones. Why? The plastic plants are often more colorful than real plants, coming in colors that are not found in in nature. They are also easier to maintain since they cannot die. And, like real plants, they offer the fish a place to hide.

However, real plants can offer systems something fake plants cannot: They can help improve the water quality of your tank. How is this? Plants need to use nitrogen and in an aquarium they are able to use the fishes' waste products. This keeps the levels low in the tank, which is a great bonus. Plants also use CO2 (carbon dioxide) for their respiration and give off O2 (oxygen) as a waste product. This is great for home tanks, as carbon dioxide build-up can be toxic and stable oxygen levels not only help your fish breathe, they can help maintain a stable pH level.

Of course, fake plants do have their own advantages: They don't drop leaves or die. Dead leaves and plants decompose, which can cause nitrogen levels in the tank to spike. This spike can stress the fish and, if it is high enough, could potentially lead to death.

Fake plants can be used to add color to fish tanks
Fake plants can be used to add color to fish tanks

Do you prefer live or fake plants in your home aquarium?

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Adding Decorations

What other decorations are safe for your tank.
What other decorations are safe for your tank.

The sky is truly the limit when it comes to adding decorations to fish tanks. You can even get a miniature replica of Bikini Bottom or Stonehenge if that is what you are into. Pet store shelves are lined with fake rocks, corals, and sunken ships, as well as many other oddities. These items have been specifically designed to be in fish tanks. This means that the materials used will not deteriorate when submerged in water for long periods of time.

There are a few things to keep in mind when picking out decorations for your tank. You need to know exactly how big the bottom of your tank is. You also need to keep in mind anything else you might already have. Are you adding plants? How many? The last thing you need to keep in mind is exactly what you want your tank to look like. Many people often go overboard when it comes to picking out decorations for their tank. It can be really easy to do, and let's face it, it's really fun to pick things out for your tank. Just keep in mind how much space you have to work with. Do you really have room for that sunken ship, fake corals, and the giant treasure chest? Sometimes simpler is better. One large piece and a couple of smaller pieces are all you need, especially if you are adding plants.

You might be tempted to add real coral and driftwood. This can be dangerous. You do not want to add any diseases or parasites to your tank. Also disturbing coral reefs is illegal in many places, not to mention extremely frowned upon in the aquarist and diver communities. Since I do not support this practice, I will not discuss it further. But, I will say this: Live coral loses its color once it dies, and wouldn't you rather have fake coral that has a realistic color instead of a white mass in your tank?

Sometimes people are tempted to add things that have not been designed to go in fish tanks. You would be surprised what some people want to use as decoration. Sharp edges, concrete, copper, and plastics that have been painted should not be put in your fish tank. Why? These items will cause problems. Copper is toxic to fish and concrete is going to leach chemicals into your tank. Sharp edges can harm your fish and should always be avoided. Paint can flake off or poison your fish. If you ever put something in your tank and notice that it seems to be flaking or the paint is disappearing, remove it immediately.

When in doubt, do not add it to your tank. It is better to be safe than sorry. After all, do you really want to endanger your fish just for the sake of having costume jewelry in your tank? Always keep in mind that no matter what you add, you want to rinse it thoroughly before it goes in.

Things That Don't Belong in Fish Tanks

Ceramics, wood, rocks, glass, plastics, coins, shells and corals may not be safe decorations for your tank.
Ceramics, wood, rocks, glass, plastics, coins, shells and corals may not be safe decorations for your tank.
  • Ceramics (if you cannot eat off it, don't put it into your tank; they can leach chemicals and heavy metals)
  • Wood (unless it was purchased at a pet store and has been pretreated)
  • Rocks (some rocks have minerals that you do not want in your tank)
  • Shells and corals (in freshwater systems, they will add calcium that the system does not need)
  • Some glass (glass is safe unless it has sharp edges or has been painted)
  • Plastics (general rule of thumb is if it smells like plastic, it doesn't go in a fish tank)

Cleaning Your Decorations

All decorations will need cleaning at some point. Here's how.
All decorations will need cleaning at some point. Here's how.

No matter what you use for decorations, except for live plants, you are going to need to clean it at some point. You are going to need some basic tools to clean your tank and decorations. Scrub brushes with bristles, soft pad scrub pads, and a gravel wash kit are a few of the items that I would recommend. Be sure to get items that go with your tank, and keep in mind that acrylic scratches much more easily than glass, so never use a rough brush or pad on an acrylic tank.

Scrub the algae off of the sides of the tank.
Scrub the algae off of the sides of the tank.

The first thing you want to do is scrub off any algae or gunk from your decorations and the walls of the tank. The hard bristled brush is good for scrubbing the decorations and the soft pads, especially with the long handles, are good for the walls. Once you have scrubbed the algae, it is time for the water change. Cleaning the substrate is easy, and you remove your water at the same time. Two birds with one stone, what is better than that? A gravel wash tube is typically an acrylic tube with a flexible hose that goes into a bucket. The acrylic tube and hose use suction to shake up the gravel and pull dirty water, detritus, and poop through the hose and into the bucket.

You can change your water and clean your substrate at the same time.
You can change your water and clean your substrate at the same time.

How often you should clean your gravel depends on several factors. How many fish do you have? Do you often overfeed your fish? Do you have live plants that lose leaves? Even if your tank has excellent water quality, you should consider doing small gravel washes weekly to remove the excess food, poop, and detritus.

Cleaning the decorations in your tank keeps them bright and the tank healthier. It is also very satisfying to see all the gunk that you remove from the gravel of your tank.

How to Gravel Wash

Methods Behind Gravel Washing


Many hobbyists opt to have a background on their tank. There are many different options for backgrounds. They come in different colors and patterns. Really, there are no wrong choices, so you can do whatever your heart desires. If you want a plain blue background, go for it. If you want a sunken ship in your background, have at it. If you want a picture of the castle at Disneyland, knock yourself out. If you don't want a background, you don't need to have one. Some people just don't like the look of the wall behind the back being visible from the front of the tank. It is really a matter of personal choice. Personally, it doesn't bother me to see the wall behind my tank, but when I do use backgrounds I make sure that I hide the tape well. I can't stand being able to see the tape; I feel it makes my beautiful tank look tacky.

On a side note: I have never seen the Disneyland castle as a background option at a pet store. But, if you happen to have a picture (and if you don't, the Internet is a lovely place), you can simple have a picture printed to the correct size and laminated. Why laminated? Think about it. At some point, no matter how careful you are, you are going to get water on the background.

© 2013 isharkbait


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    • Melanie - Texas 2 years ago

      I bought an ornament intended for aquariums at the pet store, at the same time I bought some new fish for the mature tank. I added some Rx to the tank, as I always do when adding new fish. Fish began to die. I couldn't see any symptoms, like ich or fungus. After awhile, I noticed the painted ornament was turning green (from brown). I saw that the paint was chipping, and it scraped off with a fingernail (while wet). I've removed it. Could it be that the ornament has been poisoning my fish? I did about an 80% water change and cleaning. Is there anything else I can do? Thanks

    • isharkbait profile image

      isharkbait 2 years ago

      Have you tested your water quality? But, I do agree that it is most likely the new object that you added. Do you still have any living fish in your tank? I think you are on the right path and agree with removing the decoration. I would treat your tank like it is new again. Add new fish slowly and in small numbers. Keep an eye on your nitrogen levels. If there is any toxins still in the tank from the decoration it should disparate with time and water changes.

    • Melanie - Texas 2 years ago

      Thank you for your reply. After years of not having problems, this did all start when I added the decoration. I got 7 guppies and a male molly too at that time. Some of the guppies had babies, then they all died except for one male. So did the mollies (I already had a female). Even one of the red-tipped finned tetras died, but the other 3 remain. One cory catfish died, but the other catfish are fine, including the Plecostamus. Today I notice the male guppy "feels better," when he seemed somewhat distressed before. It seems all the babies are doing fine. The tank is a 30 gallon. I had put one dose of ich Rx in there, then afterwards, some dissolving fungus pills, as a safeguard. Then it said wait a few days and do a water change before adding more pills. I'm waiting and watching to see if I even need to do that again. I had noticed one fish with a tail problem, but it could've been bitten as well. But that fish did die. The only sickness I noticed was horizontal positioning and gill inflammation, and wriggle waggle distress. What gets me is that the decoration was there, in the pet store, for aquariums. Why would they be selling things that can poison your fish?

    • sangre profile image

      Sp Greaney 2 years ago from Ireland

      I think it's nice to add decoration to your fish tank as it makes it looks less sparse. I think purchasing items for your tank in pet stores is ideal as you know that they are safe and meant for that specific purpose. It would be awful to put something in there that you shouldn't and end up killing your fish. Nice hub.

    • kim 2 years ago

      can u separate the tank so you keep bettas apart or should u do it so they don't see each other also

    • isharkbait profile image

      isharkbait 2 years ago

      They do sell dividers so that you can do just that. However, no two fish are exactly alike. One of my roommates in college had a beta tank with a built in divider so she could have two bettas. One of them would always flare his gills and try to attack the divider, the other fish didn't seem to care after the first week. It's possible that if they can still see each other they might behave in a similar fashion.

      Personally, I wouldn't put a divider in my tank. I don't think they look very appealing and I don't want to stress my fish.

    • Crisantonio 2 years ago

      That's sad. I just realized I've been putting bad things into my aquarium for years! I love adding decoration, but I never really thought about how it can affect my fish. I haven't taken care of them for about 2 years now; but the next time I do, I'll definitely keep your tips in mind. Thanks!

    • Betsy 10 months ago

      Very good condition

    • Andy 6 months ago

      hi, are there any materials like styrofoam or polystyrene that can be carved into shapes, glued together and covered in concrete!? I know the silicone/glue needs to be safe as well as the concrete but I'm not sure about the styrene or foam!?

    • Anne 6 months ago

      Long story short, I would like to put a very simple metal plant stand into my 55-gallon tank (5 fish) for decorative reasons. Will the metal or perhaps rust be harmful to my goldfish?

    • isharkbait profile image

      isharkbait 6 months ago

      @Andy, make sure that any foam you use will not leach any chemicals and is nontoxic when dry. That can be a problem with concrete over time as well. Depending on the size of your tank and the size of the item you are making it could be an issue for your system as the concrete will leach chemicals that will make your tank more alkaline in nature. (Which can be helpful if you have a large saltwater system.) I am not too sure about the styrene, but my gut says to leave it out of the tank. It might be better to use the styrofoam to make a mold and the fill the mold with an acrylic like material. Hope this helps!

      @Anne, I would advise against using metal in a fish tank. The rust will mess with your water chemistry and if the fish eat any of the rust flakes it might not be too good for them. Once the stand starts to rust it will continue to erode away. A plastic stand that is not painted would be a better option in my opinion. I'd love to see a picture of the finished product! It sound like a really neat idea. Best of luck!

    • qq 6 months ago

      what are those

    • Anonymous 5 months ago

      Is it safe to use Schleich model animals as decorations in a fishtank?

    • Gerry 4 months ago

      I broke down my tank and cleaned it to start over. I soaked the tank ornaments in dawn dishwashing liquid. The owner of the fish store I buy fish from said I should never use dish cleaner. It will kill the fish, he said. Do I have to throw all the ornaments away? Is there something I can wash those ornaments with that will neutralize the soap? I have been soaking them in plain water for the past two days.

    • isharkbait profile image

      isharkbait 4 months ago

      @gerry when I worked at the aquarium we would bleach everything (10% bleach to water ratio) after it came out of a tank. We would soak it for at least 10 minutes and then it would go into a bucket with a thio/water mix, and then we would dry it. At home you can use a splash of bleach, let it soak for a few minutes and then rinse with fresh water until you don't smell the bleach anymore. I would then let the ornaments dry completely, if there any chlorine left of them they will offgass while they dry.

      As long as the ornaments are not made of a porous material you should be fine if you bleach them. In the future I would not use dish soap to wash them as it could cause problems if you do not get all of the soap off. A hoot soak in some hot water or a little bleach water should be all you need. Hope this helps!

    • HuzaifaMotiwala 3 months ago

      Can I grow money plant in my aquarium?

      Is it harmful for fish ?

    • Katan took 3 months ago

      tack så så mycket för hjälpen jag verkligen uppskattar det ledsen jag var tvungen att översätta det hela

    • isharkbait profile image

      isharkbait 3 months ago

      @HuzaifaMotiwala. I don't think the money plant will live very long completely submerged in water. The plant itself wouldn't be harmful, but as it dies it will mess with the nitrogen cycle. If you can get the money plant to grow hydroponically then you might be able to have the roots in the tank and the tree part on the outside. It would look cool to have little neon tetras swimming around! But, I am not familiar with growing this plant hydroponically, so I don't know if it will work out.

      @Annonymous, I honestly don't know if they will be safe to use. I checked out their website and they sound like they are well made. I would say you can give one a good rinse and give it a shot. I would keep an eye out to see if the paint starts to chip off or if the figurine starts to degrade at all. I think it could be worth a shot!

    • Kai 3 months ago

      Hi I'm a somewhat beginner, I've done hours of research on new freshwater aquariums and whatnot, but I've only ever had a fish tank when i was little and don't really remember much from then. I have a huge rock collection and would like to put some of those rocks into a new tank. How can I make sure that there is nothing on the rock that will mess with my tank? Is it possible to put them in the tank when cycling it before actually putting any fish in and testing the water? Thank you

    • DISFISHYGUY 3 months ago


    • Corey 3 months ago


      I have a Male Betta. It seems like he gets lonely at times.. is there ANY type of fish that would be okay to put in with him?


    • Elton 3 months ago

      Hi, I only feed two poecilia sphenops (molly) fish in a small plastic tank and this is my first time, so may I ask that should I put some small pebbles and fake grass in it for decoration or for the fish breeding?

    • isharkbait profile image

      isharkbait 2 months ago

      @Kai, I would give the rocks a good wash before I put them in my tank. I would rinse them in hot water for a few minutes. If you think they could have something harmful to the fish on them you can soak them in bleach water for ten minutes, give them another good rinse, and let them dry completely before putting them in your tank.

      @Corey, there are fish that betas will get along with. Neon tetras would be a good match if the tank is big enough for more than just your beta. With betas you don't want any long finned fish (no mollys!), or another kind of labyrinth fish (no gouramis). But an algae eater or bottom fish (think cory cat) and neon tetras would be good tank mates.

      @Elton I would add some sort of decorations. You want the fish to be comfortable in their environment. Adding a substrate also increases surface area for good bacteria, this will help your cycle. And having plants, live or fake, will give the fish places to hide and make them feel better in the tank.

    • Brandon 2 months ago

      Hello, I have two small fish about two to three inches only. May I ask if I give them food once a day and only a few like six to eight of the fish food grain to them is it enough and ok to my fish ? Thanks.

    • Adam 2 months ago

      Hi, I have a 20cm x 10cm rectangular small fish tank and inside I feed two about 2 to 3 inches fishes inside. May I ask that I need to put air pump or not because I heard they said that it didn't have much enough of oxygen in water for the there other way to make sure the water have enough oxygen or must put air pump into my small fish tank? Thank you.

    • isharkbait profile image

      isharkbait 2 months ago

      @adam sounds like your tank is around 5 gallons. I would personally add a small airstone with a small air pump. You can get one from the store or online that is for 10 gallon and smaller tanks and that would work just fine for your fish. It's better to have the airstone than to not.

      @brandon what kind of fish are they? Different species have different rates of metabolism. I would watch your fish the next time you feed them. Are they able to eat everything you put in? Did they lose interest before the food was gone or were they still looking for more when it was gone? Depending on the type of fish it might be a good idea to give them some food in the morning and at night. Hope that helped!

    • Brandon 2 months ago

      My fish is molly how many time should I feed them per day and put how many food? thanks.

    • Jack 8 weeks ago

      Very nice post! Decorating my tank was probably the most fun part of setting up my aquarium. I like your little bit about choosing substrate and how sand can be difficult to work with. I used to use sand for one of my tanks and eventually replaced it all with gravel since it was a chore to clean out.

    • Madison B. 4 weeks ago

      Hi, I was wondering if there are any fish besides goldfish that I could put in a tank with a black telescope and a calico fantail? I would love a lot of variety with the types of fish and I want the fish to be really the stars of my tank.

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