Epsom Salt Dosage for Aquarium Unlocking the Secret to Healthy Water

Epsom Salt in Aquariums: Finding the Right Dose for Health

Fish lovers always want to provide the best for their underwater companions. The ideal thing they can do is provide them with the balanced and optimum aquarium conditions. An aquarium with an ideal environment will ensure the health of your fish friends. The appropriate epsom salt dosage for aquariums is the key for ideal aquatic habitat. 

Epsom salt has great benefits for fish and aquariums. Epsom salt has the properties to treat different disease conditions, like constipations, in fishes. A main tank can have 1 rounded teaspoon of epsom salt for 10 U.S Gallons of water. However, different tank sizes and maladies require different amounts of epsom salt. 

The salts are used in freshwater aquariums to provide fish essential electrolytes. These salts also prove to be beneficial in catering for different ailments. However, only the right dosage of these salts can make the difference. In this article, we will elaborate the dosage of epsom salt required for different fish and conditions.

Epsom Salt Dosage For Aquarium

Epsom Salt Dosage For Aquarium

Epsom salt is actually a chemical compound that contains the crystals of magnesium sulfate. It is a white crystalline solid that gives ions when dissolved in water. These ions include magnesium cations and sulfate anions. These ions are responsible for altering the pH of water and making it hard.

High concentration of epsom salt is not supposed to be permanently added in the aquarium. It is only temporarily used to treat different ailments and maintain the health of your pet fish. The dosage of epsom salt is determined by the kind of ailment you are addressing for your pet. 

Following is the table that represents the dosage of epsom salt for different fish disorders. 

Types of MaladyDosage of Epsom SaltAmount of WaterDuration
Constipations 1 TablespoonPer 1 Gallons 15 – 20 Minutes
Dropsy1/8 Teaspoon  Per 5 Gallons10 – 20 Minutes
Swim Bladder1 TablespoonPer 1 Gallons_

It is important to note that all these amounts of epsom salts should not be added directly to the main tank. Take a separate tank filled with water and add the aforementioned amounts accordingly. 

It is because the epsom salt causes the pH to change and an abrupt pH change can cause the death of your tiny fish pet. 

How to Make an Epsom Salt Bath for Your Fish?

Epsom salt baths are therapeutic for freshwater fishes. It can relieve their stress and help them in balancing the salt concentrations of their bodies. Freshwater fish deal with the issue of water retention. Due to osmosis, water enters in their body following the high concentration of salt. The salt bath helps in removing the retained water by reverse osmosis. 

Step For Giving the Salt Bath:

  1. Take an empty tank and fill it with water. 
  2. Add the epsom salt according to the amount of water taken in the tank. 
  3. Let the salt completely dissolve in the water.
  4. Retrieve the fish from the main tank and leave it in the salt bath for the duration mentioned above. 
  5. Once the time is finished, take your fish back to the main tank. 

What Kind of Epsom Salt For Fish?

White given the epsom salt bath, it is very important to choose the ideal epsom salt. Epsom salts come in different qualities, some have additives and cruel substances added in them. 

The epsom salts you will be using for your fish should be additives free. There should not be any harmful substances added in them. 

All the epsom salts have the same composition of magnesium and sulfate ions. However, the additional substances affect the quality of epsom salt. It is quite effort taking to go to the market and find the suitable epsom salt for your fish.

Therefore, we have conducted our research to find the best kind of epsom salt, saving your efforts. 

  • Health Smart’s Natural Epsom Salt (original):

It is an organic, fragrance free epsom salt. It works best as a saline laxative. It will help in easing the constipated condition of your fishes. 

Difference Between Epsom Salts and Aquarium Salts:

The following table will elaborate all the properties and differences of epsom salt.

FeaturesEpsom SaltAquarium Salt
CompositionIons of Magnesium SulfateIons of Sodium Chloride
ExtractionFrom mines & oresFrom evaporated sea water
FunctionsActs as laxative, cures swim bladder, reduces swelling and stressKills the pathogens, boosts immunity and slime coat production, removes toxins
EffectsMakes the water alkaline and hardMakes the water acidic
Role in Gill FunctionsDoes not improve the gill functions Improves the gill functions in the fishes 
DosageAccording to the disease that is being addressed According to the instructions given on the pack
CompatibilityCompatible with almost all kinds of freshwater fish but only in limited amountSome freshwater fish are sensitive to it

Usage of salts is essential for taking care of the freshwater fish. Whether it is epsom salt or aquarium salt, each serves different functions that cannot be replaced. The magnesium in epsom salts improves the nervous system and promotes good health in the fishes. 

While the sodium chloride of aquarium salt fights with fungal and bacterial infections. These salts kill the pathogens through the process of osmosis. High concentration of salt in the tank causes the pathogens to dehydrate as water moves out of their bodies. This kills the pathogens and saves the host.

It is important to understand the functions and effects of each salt to make informed decisions for the stars of your aquarium. 

Related article: Exploring the Pros and Cons of Sand in Your Aquarium

Benefits of Epsom Salts

This mineral compound has proven to have various benefits for the fish if used correctly. Even humans can take advantage of the benefits of epsom salt. This versatile compound is not actually a salt and does not have sodium in it. Still, it provides a number of benefits that can help the aquarists in keeping their fishes at the maximum health. 


  • Relieves Constipations:  Epsom salt functions as a laxative. Constipation is a common medical condition among the fishes. The medicated bath of epsom salt can help in easing the constipation and bloating.
  • Reduces Stress: Epsom salt also plays its role in reducing the stress in the fishes. In freshwater conditions, water keeps entering the fish bodies due to high salt concentration in the body (water moves towards high solute concentration). This stresses out the fishes. Epsom salt changes the gradient and causes the water to move out. Therefore, it acts as an osmoregulator. 
  • Treats Swim Bladder & Dropsy: Epsom salt also helps with the condition of swim bladder and dropsy. The accurate dosage of the salt will alleviate these conditions. 
  • Parasite Removal: Epsom salt also helps in killing the parasites inhabiting the guts of freshwater fish. The increased salt concentration in the tank destroys the parasites as all the water content moves out of their bodies. 
  • Osmotic Balance: Another important benefit of epsom salt is to maintain the water-salt balance in the fish bodies. Water tends to retain in the bodies of freshwater fishes. Epsom salt helps in maintaining the optimum balance of salts and water. 


  1. How Much Epsom Salt For a 75 Gallon Tank ?

For every 10 gallons, there has to be 1 rounded tablespoon of epsom salt. For a tank of 75 gallons, you will have to use 7 and a half tablespoons of epsom salt. The excess of epsom salt can be fatal for the fish. 

  1. What is The Best Alternative For The Epsom Salt?

Aquarium salt can be an alternative for the epsom salt. However, the importance of epsom salt cannot be substituted by the aquarium salt. Both of them have their own benefits. 

  1. How to Treat The Popeye Condition Using Epsom Salt?

This condition of popeye can be resolved by isolating the affected fish and giving it the epsom salt baths. The epsom salt will help in regulating the water balance. If not resolved, the popeye can cause the loss of vision. 

  1. What Are The Risks of High Epsom Salt Dosage?

The high dosage of epsom salt is harmful as it can cause extreme dehydration. High concentration will cause all of the fluids to come out from the fish body causing immediate death. 

  1. How The Hardness of Water Increases with Epsom Salt?

The epsom salt increases the hardness of water by increasing magnesium ions concentration in it. 1 milliliter of epsom salt in 10 liters of water increases the hardness of water by 70 mg/L. 


Epsom salt can have a wide spectrum of benefits for freshwater fishes. It is a miracle for aquarium enthusiasts as they can easily cure their fish companions with the epsom salt bath remedies. It is also essential to mention that the required and accurate dosage is the key for gaining the optimum results. 

Epsom salt is not a replacement for aquarium salt as both of them have their own benefits. Epsom salt can cure the swim bladder disease, constipations,and the dropsy in various kinds of fish. Having an organic epsom salt is a must for any fish lover and aquarium enthusiast.