Aquarium Salt Vs Epsom Salt- Which One Is Better

Aquarium owners popularly use salt in their aquariums for various purposes worldwide. But there are many kinds of salt that are used in aquariums. Among them, Aquarium salt and Epsom salt are well known. 

There happens to be significant confusion regarding which salt should be used in which case between the two. 

I have done huge research regarding this confusion and in this article, I am going to let you know which salt is best for your aquarium and which is not.

Aquarium salt mainly creates a brackish environment in the tank which is essential for some fish species. It also deals with bacterial and fungal infections, and parasites and heals wounds of fish. On the other hand, Epsom salt makes the water really hard. It can be used in severe cases to treat dropsy, swim bladder disease, and constipation as well.

Aquarium salt vs Epsom salt: Quick Differences

Comparison FactorsAquarium SaltEpsom Salt
Basic purposeTo make the water brackishTo make the water high in minerals
TreatmentsTo treat parasites, bacterial and fungal infections, etcTo treat dropsy, swim bladder, constipation, etc
Recommendation PriorityAs the first stepAs the last step (in severe cases)

Before you choose a salt to use, you should have proper knowledge about the salts. This is why I have given the basic introductions of the salts below.

What is Aquarium Salt?

API AQUARIUM SALT Freshwater Aquarium Salt
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It is basically sodium chloride [NaCl] in its raw form. The salt that we use in our kitchens is also sodium chloride but contains some minerals like iodine which are essential for humans but extremely harmful to the fish in your tank.

Aquarium salt is the raw and unmixed version of sodium chloride that is popularly used in aquariums for various purposes. It basically provides the fish with essential electrolytes that help the fish body to conduct its internal function efficiently.

What is Epsom Salt?

Epsoak Epsom Salt
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 It is basically magnesium sulfate [MgSO4] popularly known as Epsom salt. This is also a raw mineral. Though it is used in aquariums for various purposes, it is also used and consumed by humans for bodily treatments.

Now you have a fair and basic knowledge about the salts. So it’s time to look for the differences between these two salts.

Differences Between Aquarium Salt And Epsom Salt

Comparison Between Aquarium Salt and Epsom Salt


Aquarium salt is not hard on the environment of the tank. It is very soft and does not harm the fish and animals in the tank easily unless overdosed.

On the other hand, Epsom salt is very hard on the environment and on its fish and animal as well. If it is applied without proper understanding of the usage of the salt, it can affect the fish and can even cause their death.

Basic Usage

Aquarium salt is basically used to make the water brackish. Because it is necessary for certain kinds of species of fish like Mollies, Bumblebee Goby, Colombian Shark Catfish, etc to be in brackish water.

On the other side, Epsom salt is used to make the water hard. Because some species require the tank water to be very high in minerals for their survival. These fish are Guppies, platies, swordtails, and X-Ray Tetras.


Aquarium water can be used to treat bacterial and fungal infections among the fish and animals in the tank. It can also be used to kill dangerous parasites (such as Ich and Velvet) that suck blood and other essential nutrients from the fish body in the tank. It also heals the wound of the fish and helps to ease fin rots as well.

Epsom salt is recommended especially when the fish are suffering from dropsy, swim bladder disease, and constipation. A regulated and well-planned salt bath with Epsom salt can be proved very effective in these cases.

Now you know the differences between the salts. At this stage, normally the question regarding the methods of using the salts arises. I have researched about it as well and here it is.

How To Use Aquarium Salt And Epsom Salt [Quick Guide]

Use Salt in Aquarium

The Use of Aquarium Salt

You can do it within 3 levels and in each of them you can directly put salt in the aquarium but this act can sometimes be dangerous. If the salt directly falls upon any of the fish, that fish may develop a skin problem which is another crisis to deal with.

This is why it is better to get a cup of aquarium water and get the salt mixed in it and then add the water to the aquarium.

At level 1, you can add 1 spoon of aquarium salt per 3 gallons of water and wait for 5 days to see what happens. If the infections are not that severe, this dose might be helpful. But if it is not, you will have to go for level 2.

At level 2, you have got to add 1 spoon of aquarium salt per 2 gallons of water and again wait for 4-5 days to see the result. If the infections are at a medium level, this dose is sufficient to have a good result. If not, then the ultimate weapon is required to be brought into the battlefield and that is the dose of level 3.

At level 3, add 1 spoon of salt per 1 gallon of water and observe the impact patiently for 4-5 days. Hopefully, this dose will help you to get rid of the problem that you are facing. But be careful while acting level 3. Some species of fish and animals in your tank may not be able to tolerate the excessive presence of salt in the water. Have a good knowledge about it and then go for level 3.

The Use of Epsom Salt

It is very strong and hard. This is why it requires special caution while performing the process. 

Epsom salt is used to provide the fish with a salt bath. First of all, pour half of the aquarium water into a well-cleaned pot or container. Measure the amount of water you are pouring into the container and then add 1 spoon of Epsom salt per 1 gallon of water. After that, put the infected fish in that salty water and keep it there for 20 to 30 minutes.

But get the fish out of the salty water immediately if it is seen as stressful and uncomfortable.

The mentioned process will hopefully be effective to treat the diseases of the fish.

Frequently Asked Questions

Why aquarium salt is used in aquariums?

To deal with bacterial and fungal infections of the fish in the tank. It also kills parasites like ich and velvet. It heals the wound of fish and eases the fin rot of fish as well.

Why Epsom salt is used in aquariums?

It is popularly used to provide the fish with a salt bath. The salt bath helps the fish to get rid of some diseases like dropsy, swim bladder disorder, and constipation as well.

Is there any alternative to aquarium salt?

Yes. kosher salt and rock salt are excellent alternatives to aquarium salt. Just like aquarium salt, they do not have any other additives in them. These salts are also pure sodium chloride. You can use them in your aquarium without any worries.

What are Aquarium salt and Epsom salt actually?

Aquarium salt is actually sodium chloride [NaCl] and Epsom salt is actually magnesium sulfate [MgSO4].

Is iodine harmful to fish in aquariums?

Yes, iodine is extremely harmful to aquarium fish. When you are about to add salt to your aquarium, you must make sure that the salt is free of iodine. 

Can aquarium salt be added to the aquarium regularly?

No, salt does not get evaporated. This is why, if salt is added on a regular basis, it will get the concentration of the tank water high. Salt should be added when you conduct a large water change.


So, here are the things and pieces of information that I have collected through my research regarding the salt choice confusion.

To summarize the whole thing, I would say if you have bacterial and fungal infections or parasites in your fish, go for aquarium salt.

And if you find your fish suffering from dropsy, swim bladder disorder, or constipation, then you can go for a salt bath with Epsom salt.

Hopefully, till now, you have proper knowledge about both of the salts and their usages.

I hope this article will have an effective contribution to choosing the right salt for your aquarium.

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