Epsom Salt Bath for Betta Fish – Your Ultimate Guide

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Did you know that salt can be used to benefit your fish in several ways, even freshwater species, such as bettas?

But what kinds of salt are safe to use in your fish tank? When is an Epsom salt bath for betta fish appropriate? And what’s the correct dosage of salt to use?

Read this guide to learn how to use aquarium salt for betta fish treatment.

What Is Epsom Salt And How Does It Work?

Magnesium sulfate (Epsom salts) in a rustic wooden scoop - relaxing bath concept

Epsom salt is more correctly known as magnesium sulfate and is a chemical compound that comprises sulfur, oxygen, and magnesium. The chemical is named for the town on Epsom, Surrey in the UK, where the salt was originally discovered.

Epsom salt must not be confused with common table salt since it is a totally different compound, even though it has a very similar appearance. For hundreds of years, Epsom salt has been used to help cure common remedies in people. The compound is water-soluble and is sometimes called “bath salts.” In fact, people still use Epsom salts dissolved in bath water to ease aches and pains.

Today, as well as using Epsom salt in aquariums as a fish medication, the compound is used in food preparation, soil treatment, and even in cement in the construction industry.

How Epsom Salt Works In Your Aquarium

In the hobby, Epsom salt is used to maintain the magnesium concentration in marine tanks that contain stony corals.

When used to treat health conditions and disease, the parasites, fungus, or parasites that are infecting the fish soak up the aquarium salt. Once absorbed, the salt leaches water from the organisms, dehydrating and killing them.

Epsom salt is also an effective laxative that can be used to treat mild bloating and constipation in betta fish that’s caused by overeating.

What’s The Difference Between Aquarium Salt, Epsom Salt, Sea Salt, And Table Salt?

Although you can use salt in your betta’s aquarium, you must use the right kind of salt. Using the wrong salt can be dangerous to your pet!

You can read an in-depth explanation about the different kinds of salts and their use in the aquarium in our guide at this link. In the meantime, here’s a quick overview:

Table Salt (Sodium Chloride, NaCI)

Most of us have a tub of table salt in our kitchen cupboard. In the home, table salt is mostly used as a seasoning and food preservative. Salt is also handy for melting ice on your path and can even be used for keeping slugs away from tender plants.

However, table salt must never be used in your fish tank.

How so?

Well, table salt has compounds added to it, such as iodine. Anti-caking agents are also mixed with the salt to stop it from clumping. Unfortunately, all those additives can introduce dangerous chemicals into the salt, such as cyanide.

Marine Salt

Marine salt is sometimes referred to as sea salt. Marine salt contains sodium chloride, trace elements, and other salts.

This kind of salt is used in marine and reef setups to adjust the hardness, pH, and salinity levels. Marine salt is not suitable for use in freshwater tanks and should not be used to create a bath for your betta fish.

Aquarium Salt

Aquarium salt is actually derived from sea salt. However, the salt is processed to get rid of the compounds that are harmful to freshwater fish, including your betta buddy.

Many aquarists routinely use aquarium salt to help heal injuries, improve gill function, reduce nitrate uptake, and promote the production of the slime coat.

Epsom Salt

As previously mentioned, the chemical makeup of Epsom salt is different from other salts. It doesn’t contain the same elements as marine salt and is safe to use in freshwater aquariums.

Epsom salt is generally used to treat various health conditions, including swim bladder problems, dropsy, and constipation. You can also use Epsom salt to adjust the pH and water hardness in your tank.

When To Use Sea Salt

We cannot stress strongly enough that you must not use marine or sea salt to treat your betta fish.

Salt on table

Sea salt is used to set up an ocean environment for saltwater fish and other creatures. Marine salt makes the water salty and also helps to balance the pH and water hardness. 

Marine salt is extremely dangerous for freshwater creatures and plants, so never try to substitute it for Epsom salt, as that will kill your betta.

When To Avoid Using Salt

Most tropical fish and invertebrate species live in exclusively freshwater conditions where the levels of salt in the water are negligible. Although many hobbyists like to add a little aquarium salt to their tank every so often to boost slime coat production, there are times when you shouldn’t use salt at all.

Planted Tanks

If you have a tank that contains living plants, you can’t add salt to the water. If the water has high levels of salinity, your plants will quickly die. 

That’s a disaster for the water quality in the tank since plants use the nitrates in the water as nutrients. Also, plants help to oxygenate the water through photosynthesis. Finally, bettas love plants! Your finned friend uses bushy plants as hiding places and will rest on broadleaf plants when he fancies a nap.

Other Species

beautiful aquarium fish Corydoras sterbai

Many hobbyists keep their betta in a community of small, peaceful fish. Corydoras are extremely popular, cute little bottom-feeding catfish that can provide company for your betta and keep the tank tidy by scavenging scraps of food that fall to the substrate.

However, although Cories aren’t scaleless fish, they can be very sensitive to certain fish medications and to salt. That applies to many other species, too. So, always double-check that all your livestock can tolerate aquarium or Epsom salt before adding it to your aquarium.

Safety First

Bearing in mind the above potential risks of using salt in your fish tank, I recommend that you put your betta in a quarantine tank or an Epsom salt bath for treatment.

What Conditions Does Epsom Salt Treat?

There are several conditions that you can use Epsom salt to treat.


Constipation is quite a common problem in betta fish. Problems arise if you overfeed your pet, feed him a diet exclusively of dried foods, or don’t include enough live or frozen meaty foods in his diet.

Symptoms to look for include: 

  • Lethargy
  • Not eating
  • Bloated belly

Constipation can usually be treated pretty easily by fasting your fish for 24 to 48 hours, and then offering your betta some live or thawed frozen food. 

If that doesn’t cure the problem and get things moving again, an Epsom salt bath can often fix things. Basically, you add one tablespoon of Epsom salt per gallon of water to the quarantine tank.


Dropsy is a very serious condition in fish that is very often fatal. 

Once the condition is advanced, the fish’s kidneys and other organs stop working properly, and the abdominal area becomes swollen with fluid. You may also notice “pineconing,” where the betta’s scales are pushed outward, giving the fish the appearance of a pinecone. Unfortunately, once the disease has reached that stage, the fish will usually die.

However, if you catch the condition early, there is a slim chance that your betta will recover, and an Epsom salt bath can be used to reduce abdominal swelling. Use one teaspoon of Epsom salt per gallon of water in the quarantine tank.

Swim Bladder Disease

Swim Bladder disease is another common condition that affects bettas. The swim bladder is an organ in the fish’s abdomen that controls the betta’s buoyancy. Basically, the swim bladder enables the fish to swim on an even keel in the water, rise up, and swim down. When the swim bladder is compromised, the betta might swim on one side, float to the top of the water, sink to the bottom, or even swim upside down. The condition is extremely stressful for your fish, as the disability means that the betta probably won’t be able to feed or get to the surface to breathe, using his labyrinth organ.

Swim Bladder disease has several causes, including: 

  • Constipation
  • Parasites
  • Bacterial diseases
  • High nitrate levels

An Epsom salt bath can help to relieve swim bladder problems. However, before giving your fish his bath, it’s a good idea to fast the betta for 24 to 48 hours. Use one teaspoon of Epsom salt per gallon of water in the quarantine tank.

A Word Of Caution

Although Epsom salts can help to relieve some simple conditions, you might still need to treat your fish with appropriate over-the-counter medication, especially if the problem is caused by parasites or bacteria. 

Epsom salts can be very helpful in managing some health conditions and aiding recovery, but they are not a cure-all and won’t fix serious diseases, such as Dropsy.

How To Treat Your Betta Fish With Epsom Salt

The Betta Siamese fighting fish, Betta splendens Pla-kad ( biting fish ) Thai. (Halfmoon fancy white red betta ) in motion on fresh water weeds background

Now, here’s how to treat your betta buddy with Epsom salt.

Prepare The Bathtub

The Epsom salt bathtub is simply a container of around one gallon in size. Fill the tub with dechlorinated water that’s the same temperature as your betta’s tank.

Add the correct quantity of Epsom salt for the condition you’re treating. Mix the salt into the water until it dissolves completely.

Prepare The Revival Tank

You also need a revival tank where your betta can recover after treatment and before you return him to his main aquarium. 

This tank should contain ¼ Epsom salt-infused water and ¾ regular aquarium water taken from your betta’s home tank.

Gather Everything You Need

Now, gather together everything you need to treat your fish, including:

  • Thermometer with which to check water temperatures
  • Fish net to safely transfer your betta between tanks
  • Stopwatch or timer app on your phone so that you use accurate treatment times
  • Measuring spoons so that you use the correct amount of Epsom salt

Having everything on hand saves you time and hassle and makes it less likely that you’ll get your timings wrong.

Treat Your Betta Fish

Remove your betta fish from his home tank and put him gently into the Epsom salt bathtub. You’ll need to keep your betta in the bathtub for five to eight minutes only.

If you notice that the betta’s gills stop moving or he begins to lose his balance and tip onto one side, remove the fish from the tub and put him into the revival tank. 

Transfer Your Betta To The Revival Tank

Once treatment is complete, move your betta fish to the revival tank. 

The idea is to allow your pet to acclimate to less salty water conditions gradually. That’s crucial in preventing stress and potential shock that could result from putting your fish straight back into regular freshwater.

If your betta appears distressed or loses consciousness at any point during this treatment bath, move him to the revival tank until he recovers.

Return Your Betta To His Home

betta fish, siamese fighting fish in aquarium

Once the betta has spent ten minutes or so in the revival tank, you can gently replace him in his home aquarium.


In this part of our guide to Epsom salt baths for betta fish, we answer some of the most commonly asked questions about this treatment.

Q: What’s the difference between a bath and a dip?

A: The difference between a dip and a bath is the timeframe. A dip is typically of short duration, whereas a bath is a longer treatment. So, an Epsom salt bath is generally classified as a dip.

Q: Can you use aquarium salt to treat bloating?

A: No. Aquarium salt would hinder the passing of fluids, exacerbating bloating. Epsom salt does the opposite and is a much safer treatment option.

Q: Do I need to acclimate my betta before the dip?

A: The amount of salt that you use in your dip is quite high, and acclimating the betta beforehand would overexpose him to the dose more than is necessary.

Q: Can my betta pass out?

A: Yes, he can. Loss of consciousness is generally a stress reaction to the unusual conditions in the dip. Usually, unless the betta is seriously sick and weak, once you put him back into his preferred, non-saline environment, he will return to normal pretty quickly.

Q: How often can I use an Epsom salt dip for my betta?

A: If you’re using an Epsom salt dip to treat constipation in your betta, you might need to put him in the dip two or three times to get things moving. Other conditions, such as Dropsy and Swim Bladder Disease, are more serious and should be treated with appropriate medication for the cause of the condition.

Overexposure to Epsom salt can be harmful to your fish and this treatment shouldn’t be used routinely.

In Conclusion

Betta splenden fish

Epsom salt can be used to treat several conditions in betta fish, including Dropsy, Swim Bladder Disease, and constipation. However, you should never overexpose your freshwater fish to Epsom salt, as that could be harmful to your pet.

If your betta buddy’s condition doesn’t improve following his Epsom salt bathtub experience, you need to work out what’s causing the problem and try using an appropriate over-the-counter medication to treat him.

Did you give your betta fish an Epsom salt dip, and did it work to cure his problem? Tell us about your experience in the comment box below!

Alison Page has been an avid fish keeper for over 35 years and has owned many different species of freshwater tropical fish including bettas. Currently Alison has two large freshwater tanks. The first tank has two huge fancy goldfish who are almost ten years old and still looking as good as ever. In the other, she has a happy community of tiger barbs, green tiger barbs, corydoras catfish, platys, and mollies.

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