Can You Put Corals In a Freshwater Tank?

Hi, this is your friend Clifton Ervin, the founder and chief editor of this site, Aquariumwolf. I completed my graduation in marine biology and became...Read more

Hey fish lovers! As you are here, you are not only concerned about the health of your aquarium fish, but you also want to decorate your fish tank attractively, right? That’s why you need to know which decorative materials are harmful to your fish to keep them safe.

One common question popping up in almost all aquarium lovers’ minds is, can you put corals in a freshwater tank? Well, the answer to this question is a bit controversial, so let me explain to make it easier for you.

As I said, it is a controversial question; the answer has two different perspectives. You can use corals to make your aquarium look more appealing, but it has to be dead corals. Also, you can’t just put dead corals directly in a fish tank. You must take some precautions first.

On the other hand, when it comes to live corals, they are almost prohibited and not recommended to use in a freshwater tank by experts.

To put it simply, if you are determined to use corals to decorate your aquarium, use dead corals instead of living corals. Because live corals create toxicity in water. In addition, their chemical materials drastically change the pH of the freshwater tank, resulting in the hardness of the water.

You may already know that high pH and hardness of water are harmful to the fish. And, in the worst-case scenario, the high pH leads the fish to death.

Want to know more about the topic? Let’s get straight into it!

can you put coral in a freshwater tank

6 Precautious Steps To Follow Before Adding Dead Corals to a Freshwater Tank

You might know that you can put any kind of coral, dead or alive, in a saltwater tank. Because corals have the ability to live under high pH water. However, in the case of fresh water, you can only put dead corals with certain precautions.

Here, I’m going to mention some precautious steps that you should follow before using dead corals in your freshwater tank. First off, let’s get to know them at a glance, and then we will go into further details:

  • Remove Organic materials from the Corals
  • Remove Outer materials (Dust or other likely substances)
  • Clean the Corals with hot water
  • Cover the corals with resin or epoxy
  • Add a few corals once a week (Don’t rush the process)
  • Refill the tank water once a week

Let’s Dig A Bit Deeper Into Each Of These 6 Steps To Make It Much Easier For You:

1. Remove Organic Materials from the Corals

The first and foremost thing you have to do before putting the corals into the aquarium is to wash them well. So that there is no organic material left on the surface of dead corals.

So, rinse the corals thoroughly because if a single organic particle remains, it will pollute the fresh water and end up threatening the fish.

2. Remove Outer materials (Dust or other likely substances)

Almost all aquarium shops supply dead coral skeletons thoroughly rinsed by water and free from organic materials.

So, you might think you can put the corals in the water directly, but you are wrong in that case. If any dust or outer materials remain on the surface, then you’ll have to clean the corals again so that they cannot pollute your tank’s water.

3. Clean The Corals With Warm Water

Before putting the skeletons in the freshwater tank, one crucial step is to clean your selected corals with warm water. It is better not to use cold water in terms of washing corals because the bacteria on the surface may survive if you use cold water instead of warm water.

Clean The Corals With Warm Water

4. Cover The Corals With Resin Or Epoxy

If you want to make your corals more colorful and crafty and also ensure the safety of your fish, then you can use resin or epoxy for decoration. Because resin and epoxy are harmless chemical substances used to color corals.

5. Add A Few Corals Once A Week (Don’t Rush The Process)

Rushing to decorate your aquarium with corals can be harmful. Because, the water in your tank needs time to adjust with the CaCO3, which is the primary material of corals. Thus, you should put two or three corals weekly to keep the process steady.

6. Refill The Tank Water Once A Week

The dead corals contain Calcium Carbonate that may cause hardness of water due to the high pH range (over 9.6). That’s why you must refill the tank once a week to keep the tank water safe for fish.

What Happens if You Add Fresh Live Corals to a Freshwater Tank?

If you are using a saltwater tank as your aquarium, then you can put live corals in your tank without any concern. Because the buffer system of this type of tank is made for high absorbance of alkaline substances.

But, mind you, live corals are harmful to freshwater tank fish as they have a low tolerance for alkaline substances.

Now, let’s get to know what might happen if you consider adding live corals to a freshwater tank:

1. Transforming into Hard Water

The main disadvantage of using live corals in the freshwater tank is the water turns into hard water. As mentioned above, corals contain calcium substances, mainly Calcium Carbonate, which play a crucial role in making hard water.

Let me tell you a bit more about hard water for making the concept clearer to you. Hard water is mainly high in pH, and this increased pH range is caused by three anions, mainly CO3(2-). The water is called hard water when these cations are turned into salt by creating bonds with any cation.

Hard water is extremely hard for fish because it decreases the DO (Dissolved Oxygen) of water by increasing the COD range (Chemical Oxygen demand). As a result of reducing oxygen in the water, fishes struggle to live underwater.

Moreover, their gills and the surface of the eyes may get harmed too. Remember that chronic hard water caused by the corals of the tank may eventually lead the fish to death.

2. Releasement of toxic Ammonia and Nitrogen

Bacteria can grow on the surface of live corals, and these bacterias are more likely to release toxic ammonia and nitrogen into the water.

In addition to that, also bear in mind that, though the dead corals in the freshwater tank are less harmful than live ones, they do not entirely remove the danger. Dead corals can also release these toxic substances if they are not washed properly before use.

Releasement of toxic Ammonia and Nitrogen

Remember, the presence of ammonia and nitrogen will most likely harm the reproduction cycle of fish. Due to the existence of these materials, the energy the fish get from their food will not be efficient enough for their reproduction. Also, nitrogen emitting from the bacteria of corals may harm the growth of the fish.

So, you should remove the corals immediately if you see any bacterial presence on their surface and clean the tank.

3. Harmful To Immunity And Production System Of Fish

Corals’ chemical substances, like ammonia, nitrogen, or carbonate salts, decrease fish productivity. Also, it damages the immunity system of the fish. Even the surface and skin of the fish become pale, and they get an infection from these substances.

The chemical substances dissolved in water from the corals will also harm the cellular membrane of fish. In addition to this, the chronic presence of those chemicals can make fish blind too.

4. Imbalance in the pH range

As I’ve already said, the calcium carbonate of the coral will turn freshwater into hard water. And, hard water will most probably increase the pH of your tank water.

Imbalance in the pH range

Keep in mind that, the pH range of freshwater must remain in the range of 4.5 to 9.5. If the pH rises above 9.5, then it will cause harm to the fish in the aquarium.

Frequently Asked Questions

Don’t forget to check the FAQ section below, it’ll clear your confusion if there is any question still knocking on your mind.

Can coral grow in freshwater?

No, live corals can’t grow in freshwater as the life circle of corals revolves around salt water. That’s why you will never find corals in river water. Corals are only found in seawater far from the link between rivers and seas.

How hard is it to keep the coral alive in a fish tank?

It is pretty hard to keep the corals alive in the aquarium because you have to maintain the pH range in a certain way of your saltwater tank to complete the nutritional needs of the corals. Also, a specific temperature has to be maintained.

Final Words

Well, that’s all there’s to it, people. After reading the article, hopefully, now you are clear about the safety of your tank’s fish. Now you will be able to make wise decisions regarding the decorations of your water tank by taking some precautions first. After all those words, I am sure you got the answer to this burning question, can you put corals in a freshwater tank?

To wrap it all up, you are not supposed to use live corals in your freshwater tank. To make your freshwater tank more appealing, you can only use dead corals. But you must follow the aforementioned precautions before using dead corals in the tank so the tank’s fish are safe. Now enjoy making the perfect fish aquarium for your house or office.

Thank you so much for dropping in today, you guys are the bee’s knees!!!

Hi, this is your friend Clifton Ervin, the founder and chief editor of this site, Aquariumwolf. I completed my graduation in marine biology and became an Ichthyologist. One of my favorite hobbies is aquarium keeping; therefore, I love to talk about fish keeping, breeding, food behavior, etc., and much more relevant to aquarium maintenance. I have created this site Aquariumwolf, to share my 20 years+ of experience and knowledge with all new to this journey.

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