Symptoms Of Too Much Salt In Aquarium (And How To Avoid It)

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by Jason Matthews



When properly used, aquarium salt can be highly beneficial for fish and other aquatic life and in some cases even prevent infections and help lower their stress levels, keeping them happy and healthy. However, if used improperly, salt can kill off all your aquatic life as well as your plants which is why it’s so important to not only use the right type of salt but also the correct amount. 

Taking care of your prized aquatic environment

You need to check the type of water and fish, as water that is soft and acidic can get worse with the addition of too much salt especially if you add fish like catfish and koi that cannot tolerate too much salt. However, hard water can tolerate the addition of salt along with fish like goldfish, guppies, and more that respond well to extra salt. Plants, on the other hand, especially freshwater plants and algae, react badly to salt and even a small amount can cause them to die. This can also affect snails that need to always be transferred to another tank when adding salt. 

Always make it a point to dissolve the salt in a separate container before slowly and evenly adding it to the tank, you will also need to monitor your fish very closely and check how they are adjusting to the new addition of salt, if your fish are stressed or behaving in an unsettling manner you will need to completely replace the water. 

Keep in mind that salt isn’t removed by the filters and does not evaporate, once added to the tank it remains there until the water is changed. You will not need to refill the salt in the tank but in fact, you will need to keep refilling the water as less water can mean a higher salt concentration which can be harmful to your fish. 

So, what are the symptoms of over-salting an aquarium?

Most professionals will advise you to add a 0.3 salt level for treating any illness otherwise for daily use you can add a kg of salt to every 265 gallons of water. Always start small and slowly go up and always spread out the salt intake over a couple of days while closely monitoring your fish. Adding too much salt can be deadly and since salt does not evaporate, you’ll need to clean and replace the water each time, depending on the volume of the tank. 

So, what are the symptoms of too much salt in aquariums?

  • It kills most of the plant life

If you have a lot of live plants in your tank, added salt can easily damage them or even kill them, the same can happen to scaleless fish as they can be quite sensitive to salt. Avoid using ordinary salt filled with chemicals and additives, instead, always invest in a natural salt that’s safer for your fish and can offer them the vitamins and minerals that they require. 

too much salt killing aquarium plants
  • Can be deadly to your fish

Another symptom of too much salt is that you’ll find that it kills most of the live plants, fish as well as snails in the aquarium. Fish will often look stressed and will frantically be swimming around near the surface gasping for air, vigorously darting around the tank, and will even lose their appetite. Most fish will even develop a coat of slime and get dehydrated which eventually leads to death. 

sick fish from too much salt

Related: How to safely mix water for a saltwater aquarium

Can you get salt out of a fish tank?

As mentioned before, aquarium salt does not evaporate nor does it get filtered out and so if you have added too much salt you would need to change the water entirely and clean the tank as well as immediately move your fish to a safer location while doing so. You will then need to safely use vinegar to remove any of the salt creeps and scrub the tank of any salt deposits on the glass. 

If not cleaned, these deposits can gather over time on the glass and make the tank look murky. In certain extreme cases, you might need to soak a paper towel in the solvent and place it on the glass allowing it to soak in overnight, and then simply clean it well in the morning. Always sterilize any accessories that you place in the tank including shells, small homes for fish, and more. 

Once cleaned well, you can remove the pieces, allow them to dry, and then place them in the tank. The same goes for any pebbles or rocks you find outside that need to be cleaned properly before being placed in the tank. 

Related: Aquarium Salt vs Rock Salt

Does aquarium salt affect ammonia levels?

The only type of salt that can raise the ammonia levels and pH in an aquarium is marine salt. It works to increase the hardness of the water and can affect the volume of the water as well by binding with the hydrogen atoms in the water. This ammonia can be toxic to fish and salt mixes if not monitored can cause ammonia levels to increase especially if you add it to the tank along with tap water. 

So how can you keep the ammonia levels down?

The best way to keep the ammonia levels low in your fish tank is to add cycled filters and use a concentrated water ammonia-removing filter. This along with changing your water religiously every couple of weeks can help lower the level of ammonia in the tank, you will also need to remove any decaying vegetation, monitor your fish feed, and ensure that the salt you add is great for healthy bacteria and algae growth that your fish can feed on. 

Experience the Art of Proper Fish Keeping 

At the end of the day, always do your research and look for organic and natural salt brands that have a lot of essential nutrients, vitamins, and antioxidants as well as minimal chemicals. While salt can be used in small doses to treat sick and diseased fish, you should avoid adding too much salt to the water and always ask your local pet shop or fish expert how much salt to add. 

If added in the right amounts, salt can improve the health of your fish, aid in recovery from illnesses, remove parasites and harmful bacteria from the water, and increase gill function along with the formation of their slime coat which allows them to avoid getting ill.


How do I remove salt from my fish tank?

To remove salt from your fish tank, perform regular water changes, replacing a portion of the saltwater with fresh, dechlorinated water. This will gradually reduce the salt concentration until it reaches the desired level.

What happens if you put too much aquarium salt?

If you put too much aquarium salt, it can lead to fish stress, gill damage, dehydration, invertebrate sensitivity, and aquatic plant damage. Monitor and maintain proper salt levels according to the specific needs of your fish and plants.

How long does it take salt to dissolve in a fish tank?

Salt typically dissolves in a fish tank within a few minutes to an hour, depending on factors like water agitation, temperature, and the type of salt used. Make sure to dissolve the salt completely before adding it to the tank to avoid concentrated pockets that can harm your fish.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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2 thoughts on “Symptoms Of Too Much Salt In Aquarium (And How To Avoid It)”

  1. I’m a beginner fish keeper so please excuse any ignorance I may have but have been reading many blogs to try and educate myself.
    I used some aquarium salt in my fresh water tank to try to treat a fish that seemed constipated and or stressed. When that didn’t work and that fish had died, I did a 50% water change. Now my last fish is acting very skittish and hides in a rock only to come out when it’s feeding time. Did I do too much of a water change and should I add back salt to help?

    • It’s generally not a good idea to use aquarium salt in a freshwater tank unless you’re treating a specific condition, such as a bacterial or fungal infection. Aquarium salt can be harmful to fish if used incorrectly or in excessive amounts, so it’s important to use it only as directed.

      In your situation, it’s possible that the aquarium salt you used may have stressed your fish or even contributed to its death. It’s also possible that the 50% water change you performed was too much for your fish to handle, which could be why it is now acting skittish.

      If your fish is still alive and appears healthy, I recommend not adding more aquarium salt to the tank. Instead, focus on maintaining good water quality and providing your fish with a healthy diet. If your fish continues to show signs of stress or illness, it may be best to consult a veterinarian specializing in fish health.


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