What Salt to Use for Sick Fish in Aquarium?

-- By Carol

The next time you see your fish showing signs of distress or disease, you can give them a quick treatment in no time.

This simple treatment can be lying on your kitchen table or cabinet!

Salt is one of the most widely used substances to treat freshwater aquarium fish thanks to its amazing antibacterial and disease-fighting properties.

But what salt do you have to use? And how are you supposed to use it?

Keep reading this post to find out the answers and everything else you need to know about using salt to treat your fish.

Table of Contents

What Salt to Use for Sick Aquarium Fish

Sodium chloride (NaCl), commonly known as table salt, is arguably the best medicinal product on the market when it comes to treating sick aquarium fish. It’s very effective against bacteria, fungi, and external parasites that are the major culprits behind a number of fish diseases.

Not just that, sodium chloride is also super cheap, readily available, and never really expires.

You can use it to prepare solutions over a wide range of concentrations very easily.

It is, however, important to remember that most varieties of commercially produced table salt are usually iodized and packed with other additives such as anti-caking agents.

These impurities can be harmful to your fish as well as for the overall water chemistry inside the aquarium.

Even though it’s best to use aquarium salt, you may use table salt as long as it’s non-iodized and 100% pure.

Types of Aquarium Salts

There are two broad categories of aquarium salts: marine aquarium salt and freshwater aquarium salt.

Freshwater aquarium salt is also known by the names of livebearer salt or tonic salt.

Some brands of freshwater aquarium salts can contain a little more than just plain sodium chloride such as small quantities of other mineral salts such as calcium chloride and magnesium chloride.

These act as buffers against pH changes. These are sold in small containers and the required dosage is typically not more than 1-2 teaspoons per gallon.

Marine aquarium salt is produced to create artificial seawater inside the aquarium.

Therefore, it mimics natural seawater in terms of mineral composition but with a much higher buffering capability.

To put it simply, artificial seawater is much more capable to resist pH fluctuations in between water changes as compared to natural seawater.

This also makes marine aquarium salts much more expensive and they are normally sold in larger bags or buckets.

How Does Salt Act as Disease Defense Mechanism for Aquarium Fish?

Salt helps aquarium fishes by killing microorganisms and parasites by dehydrating them.

When you add salt in the aquarium, it increases the salinity of the water.

This disturbance in salt concentration causes stress in bacterial and fungal cells.

To balance the salt concentration and osmotic pressure on each side of the system (microbial cells and aquarium), water gets sucked out of the microbial cells causing dehydration and finally death.

These tiny microorganisms and parasites get depurated way faster than fish or plants and end up dying. There are certain exceptions to this general mechanism.

Few microorganisms can tolerate high salinity conditions so salt may not be a 100% fool-proof solution.

Can You Use Salt in Freshwater Aquariums All the Time?

No, you should not use sodium chloride salt in your freshwater aquariums on a daily basis or as a preventive measure or health booster.

You can think of it as popping up antibiotic pills without any disease just to minimize the risk of getting an infection.

The pills do have side effects and they will kill good bacteria inside your body.

Similarly, continuous exposure to saltwater can make any disease-causing organism get past the protective salt barrier, and then it will require a much higher concentration to be killed.

A high salt concentration can be detrimental to the fish.

Therefore, you must use salt in small amounts and only when it’s necessary.

How to Use Salt to Treat Aquarium Fish

Salt treatment for sick aquarium fish can be done at three levels.

You can start with a very low salt concentration and gradually increase if the disease symptoms persist. Here are the details.

Treatment Level One: 1 Tablespoon for 3 Gallons of Water

This is how you begin with your salt treatment.

You need to add 1 tablespoon of salt per 3 gallons of aquarium water. There are two ways to add salt to the aquarium.

You can pour it directly into the tank or dissolve it in a small amount of water first and then add the solution into the tanks.

The second method is more preferable.

This level of salt is best for mild cases of bacterial or fungal infection.

Additionally, it gently irritates the slime coat of your fish, causing them to produce more protective mucus around their bodies.

This way, they can block further microorganisms and parasites from attacking them. You can keep the fish in this salt solution for 4-5 days.

If the fish get better, you can change the water after a week. If not, you may have to increase the salt concentration.

Most fish can easily tolerate this concentration of salt so it’s very safe except for a few cases such as the anchor catfish.

Treatment Level Two: 1 Tablespoon for 2 Gallons of Water

The next level of treatment involves increasing the concentration to 1 tablespoon of salt per 2 gallons of water.

Level 2 treatment is capable of fighting against diseases that are unresponsive to the initial treatment or those that are more advanced.

This level of treatment can also be used to treat Ich.

This is a very common disease among fish caused by protozoa and it’s also known by the name of white spot disease.

You have to use this treatment for at least a period of 10 days. However, if the symptoms worsen after 5 days, you should try increasing the concentration.

Treatment Level Three: 1 Tablespoon for 1 Gallon of Water

If the previous two levels of salt concentration are ineffective, it’s time to step up your salt treatment.

You will now use a higher concentration of salt using 1 tablespoon of salt for every gallon of water.

This high concentration of salt will be capable of knocking out all disease-causing culprits entirely.

However, this level of treatment is not for every fish. Scale-less fish will not be able to tolerate the high salt concentration at level 3.

Therefore, you will have to conduct some research on your fish species with respect to their sensitivity to salt concentrations.

Generally, danios, silver dollars, rasboras, tetras, most cichlids, and livebearers are quite tolerant to salinity.

Others that can also be quite hardy in salt are Neocardina cherry shrimp.

What Should Be the Duration of the Salt Treatment?

You can leave the fish in saltwater until their symptoms improve and they start looking healthy.

However, it’s recommended not to go longer than 10 days for each level of treatment.

You can also consult your veterinarian before starting the treatment and perhaps supplement it with certain other medications.

Once the fish recover from the disease, you must remove the salt by doing water changes.

When it’s time to end the salt treatment, you should perform a thirty percent water change without adding any salt and then wait for about 7 days for observation.
In case there are no signs of an infection relapse, carry out another thirty percent water change. Again, you should replace salt and wait for one more week to observe your fish.
If the disease comes back, you will either need to go back to the salt concentration that you used originally or add a little more salt to increase the concentration. This is because the original salt concentration may not have been powerful enough to complete eradicate the disease or your fish didn’t get to spend sufficient time under saline conditions to dehydrate the pathogens.

Using Salt in Planted Aquariums – Is it Safe?

It’s never recommended to keep your plants in a saline environment as salt can have damaging effects on the plant.

While some plants are able to withstand salty water, most will start dying especially if the treatment goes too long.

Therefore, adding a higher concentration of salt to planted aquarium should be avoided.

Instead, you should take out the fish from the aquarium and transfer them into a temporary tank (called the “hospital tank”), and carry out the salt treatment in there.

Once your fish get better, you can put them back into the original aquarium.

Final Words

Sodium chloride in its pure form is an effective remedy for common aquarium fish ailments.

It can work as a great health aid for your fish if you want them to live with a longer lifespan.

However, care has to be taken when using salt in freshwater aquariums as very high concentration can actually do more damage than good.

We hope this article will be useful for you the next time your fish get sick and you want to give salt a try!

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