Home Goldfish Tank Should You Add Freshwater Aquarium Salt to a Goldfish Tank?

Should You Add Freshwater Aquarium Salt to a Goldfish Tank?

by Christina Crowe
16 comments
Freshwater aquarium salt is 100% fish safe

Photo by Dubravko Sorić (Flickr)

“Water, water everywhere and not a drop to drink.”

You might know this quote from The Rime of the Ancient Mariner. A man is adrift on the ocean, water as far as the eye can see and yet dying of thirst because people can’t drink salt water.

Tough break.

But for goldfish, freshwater aquarium salt (when used effectively) can provide many benefits. Too much, of course, and you’ll do more harm than good – just like with any substance that is overdosed.

Already know the benefits? Skip to the aquarium salt treatment guide to determine how much salt to put into your aquarium

But if you’re new to salt treatments, the very concept might sound ridiculous. Why on earth would you add aquarium salt? After all, goldfish are freshwater fish.

Why Salt Is Good for Goldfish (Not So Much for Humans)

Actually, adding salt to a freshwater tank isn’t too unheard of. Not at all.

You might already know that salt reduces stress. You’ve probably heard that salt treats parasites, even. But one benefit that isn’t often talked about is osmoregulation.

The cells in your goldfish contain a specific salinity (or salt and water balance). At every moment, small traces of salt trickles back into the water from your goldfish’s body. To keep up with this, your goldfish have to constantly reabsorb small amounts of salt from the environment.

Luckily, aquarium water naturally provides some salt – though the amount of salt in a freshwater aquarium is much smaller than the salt density in a saltwater aquarium. And rightly so, because too much salt could seriously hurt – even kill – your goldfish!

But by adding a small amount of freshwater aquarium salt during stress, you’re boosting the salinity in your aquarium just enough to make things easier for your goldfish. This can have all sorts of benefits.

Freshwater aquarium salt can reduce stress



  • Freshwater aquarium salt reduces stress. Some goldfish diseases can stop the gills from functioning properly. If your goldfish don’t absorb enough electrolytes from the water (because they’re under stress), they could go into an osmotic shock. Salt replenishes much-needed electrolytes, helping your goldfish maintain a healthy flow of oxygen and carbon dioxide.
  • Aquarium salt helps goldfish recover faster from infections. When small amounts of aquarium salt are added, your goldfish don’t have to work as hard (or absorb as much water) to maintain the salt density in their bodies. Your goldfish actually save more energy to fight off diseases and heal painful scrapes – very much like how rest helps you and me recover from nasty colds.
  • Aquarium salt kills off parasites. Freshwater aquarium salt disrupts the salt/water balance in the cells of harmful organisms, dehydrating them until they let go of your goldfish and eventually die off. For this reason, salt baths are particularly effective treatments for parasite infections.
  • Freshwater aquarium salt prevents nitrite poisoning. If your filter suddenly stops working or you’ve just set up a new tank (that isn’t fully cycled), nitrite levels may spike – and nitrite poisoning can be deadly! Chloride ions in aquarium salt reduce nitrite absorption, preventing nitrite poisoning when nitrite levels are high.

Some invertebrates (like snails) and plants are very sensitive to salt. And if your aquarium uses zeolite to cut down on ammonia, effects may be reversed during a salt treatment. Always remove sensitive invertebrates and zeolite before adding any type of salt.

Freshwater aquarium salt can be used as a preventative to help keep your goldfish healthy or as a treatment to cure common goldfish diseases (especially when parasites are to blame).

But what type of salt should you use? Let’s look at your options.

Keeping Salt Goldfish Friendly: 3 Types of Freshwater Aquarium Salt

Some salt (like table salt) can be bad news for goldfish. Luckily, you’re not just limited to table salt.

Adding salt regularly? Aquarium salt is a good choice. But if you want to keep your options open, rock and kosher salt are healthy alternatives.

  • Freshwater aquarium salt is quite different from the salt you keep in your kitchen cabinet. Created from evaporated sea water, this salt contains no harmful additives like table salt and is specifically made for freshwater aquariums. Plus, you can buy it from any pet shop where fish are sold.
  • Non-iodized rock salt and kosher salt are made up of just sodium chloride (unlike table salt that can contain iodine and calcium silicate). No extra ingredients are added, making these types of salt great for goldfish aquariums.

When introducing salt to the aquarium, never use table salt that contains additives. Toxic additives and spices in table salt can be deadly to goldfish.

Aquarium salt is a powerful tool against stress and parasite infections. But don’t overdo it!

Like all freshwater fish, goldfish can only take so much salt before it becomes harmful. When performing a salt treatment, keep an eye out for signs of stress. Reduce treatment or stop treatment altogether if your goldfish seem agitated.

Do You Treat Your Aquarium with Salt?

What type of salt do you use? Do you regularly add freshwater aquarium salt as a preventative or only as a treatment when you notice signs of stress?

Add your suggestions to the comment field below!

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16 comments

Chantal Lee October 5, 2014 - 12:14 pm

Great page! Super insightful and concise :). Just a quick question
I have a 20 gal tank with a few tropicals and one goldfish (I know this is usually a “No no” but it seems to be working out well)
Just recently my goldfish has developed Ich 🙁 (and also fin rot (I think?) Anyways I just read your article about treating with salt rather than going straight for meds and was wondering how this would affect my tropicals in the tank?

Thanks,

Chantal

Reply
Christina Crowe December 17, 2015 - 6:51 pm

Hi Chantal,

If your goldfish has ich, there’s a high chance your other fish will get it too – ich is very contagious! Unless you have fish sensitive to aquarium salt, the salt itself shouldn’t harm any of your tropicals.

Otherwise, if you did want to try treating your goldfish with salt, you could move either your tropicals or goldfish to another tank and treat the aquariums separately.

Reply
Jessica October 18, 2014 - 7:22 pm

I have been thinking about adding salt with my blackmoor goldfish but I also have some catfish in the tank..? I have been told before that sometimes salt does harm to catfish. Do you know anything about this? I would like to add a little cleanliness to my tank for my goldfish. Please help.

Reply
Christina Crowe December 17, 2015 - 6:45 pm

Hi Jessica,

Unfortunately, I’m not familiar with raising catfish as I’ve never had catfish in any of my aquariums. However, after doing a bit of research, I found that some people recommend using half the regular dose of aquarium salt for these type of fish. Maybe you can try that – or less if it makes you nervous.

Goldfish don’t necessarily need aquarium salt on a regular basis, so you can do without the salt and your fish should be fine. I only add salt when my goldfish are stressed or sick, so it might help to keep sick goldfish in a hospital tank and treat that hospital tank with aquarium salt and the appropriate medication – that way your catfish aren’t under any unnecessary stress.

Hope that helps!

Reply
Malik Saleem November 19, 2014 - 5:40 am

Dear Sir,
I have 10 gallon aquarium. I have bought it just 1 month ago. In the starting days I have lost 8 fish and now I bought more fish. Someone told me to use salt and I stirred the kitchen cabin salt. At this time, my fish have been passed many days but now my 2 fish are sick. I have 1 fighter, 1 guppy, 2 goldfish and 2 more which I don’t know their name. My 2 goldfish are sick and one is grave sick. Someone told me to stir the anti biotic injection into the water and I did but my fish is still sick and fish is about to die. Here is no shops for fish or aquarium. I have to go to other city for the treatment and it will be very hard for me. Please, tell me, what should I do for the first aid

Reply
Christina Crowe December 17, 2015 - 6:35 pm

Hi Malik,

It looks like you might have an overcrowding problem. Two fancy goldfish will need a 30-gallon tank at the very minimum – goldfish contribute a ton to ammonia and ammonia buildup is never good for fish. What kind of filtration system are you using? Have you tested the water for ammonia, nitrite, and nitrate?

Hopefully you were able to solve the problem. If not, I suggest moving your goldfish to a larger tank and keeping the 10 gallon for all of your tropical fish. That way, any sick goldfish will have a lot more room and cleaner water to recover. Since the new tank won’t be cycled, you’ll want to pay very close attention to those water parameters – read this article on water testing if you need help. Make sure ammonia and nitrite don’t get too high – both should be at or near 0ppm. If those levels start to rise, change 25%-40% of the water depending on how much ammonia and nitrite in the water.

Also, you should never put in the tank table salt designed for kitchen use. Instead, always go for non-iodized rock salt, kosher salt, or freshwater aquarium salt formulated for fish.

Reply
Malik Saleem November 19, 2014 - 5:46 am

I have no experience about the fish but I like to have aquarium and fish. If the loses will be continued to me than I will leave it but I don’t want. please tell me suggestions in simple manner

Reply
Christina Crowe December 17, 2015 - 6:18 pm

Hi Malik,

Whether or not to use aquarium salt is completely up to you. I prefer to add a bit of salt whenever my goldfish seem sick or stressed, but that doesn’t mean you have to use aquarium salt in your own tank.

If you need help on how to add salt to your aquarium, see my salt treatment guide here.

Reply
ron January 21, 2015 - 8:13 pm

never told amount of salt to add to the aquarium

Reply
Christina Crowe December 17, 2015 - 5:56 pm

Hi Ron,

You can determine how much aquarium salt your tank needs in the aquarium salt treatment guide here. Thanks for reading!

Reply
Freddy February 17, 2015 - 4:18 pm

This was another well written article. Thank you. I don’t use aquarium salt as a preventative measure but I am prepared to use it for external parasites that may infect my fish. My one concern for using salt as a preventative is brought out by David E. Boruchowitz in his book ‘Aquarium Care of Goldfish’. He says that if the fish are healthy, it may not be a good idea to have them produce extra slime due to the salt treatment, as the salt may be messing with what the natural world has given them in slime volume. Yes, we are talking about slime lol. Again though, interesting article. Take care.

Reply
Christina Crowe December 17, 2015 - 6:13 pm

Glad you found the article helpful, Freddy!

I do agree with you. I actually changed my salt treatment routine about 5 years ago. I used to put in a little aquarium salt after every water change. Now I only treat the tank with salt if my goldfish are stressed (after a move for example) or when I suspect my goldfish might be sick. I did notice the salt treatments seem more effective when used this way – and if you’re raising goldfish in a healthy environment and taking the necessary safety precautions (like quarantining new fish before placing them in the main tank), it’s very unlikely that your goldfish will get sick anyway. So you may not need that extra preventative step of using aquarium salt regularly.

But really, it’s completely your choice – there’s no right or wrong method. If later on you decide that you prefer using aquarium salt on a regular basis, that’s completely fine. 🙂 I think it’s important to know the reasons behind a particular method so you can always make an educated decision.

Reply
Freddy December 18, 2015 - 10:21 pm

Thanks for the very thorough reply Christina! I decided to use salt as a preventative and it is working out well. Thanks again for your time in replying to me!

Reply
Christina Crowe December 18, 2015 - 11:24 pm

You’re very welcome! Happy to hear the preventative method is working out for you. 🙂

Reply
PJ Bear June 9, 2015 - 9:21 pm

This article failed to mention the most important thing: How much salt do you add to your goldfish aqaurium?! =(

Reply
Christina Crowe December 17, 2015 - 6:02 pm

Sorry for the confusion! I talk about how much aquarium salt to use in your tank here, depending on your salt treatment preference (whether you want to use salt as a preventative against infections or only when your goldfish are sick).

Let me know if you need anything else!

Reply

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