Will trace amounts of salt kill fresh water fish?

  • #1
I have a water softener that makes every tap in my house salt water. I let the salt run out in the water sofener and then waited awhile so the salt would get washed out of the taps. I also let some water on a plate evaporate to see if it left salt, after the water evaportated it did leave something behind but it didn't taste like salt and my water has a lot of minerals in it so I think that is what it is. So will small trace amount of salt kill my fish? I can use my hose from my backyard but that has coli-forms in it so I think that will kill my fish too.
  • #2
I'm assuming it's such a trace amount that you can't even taste it, right? Such minute amounts should have no effect whatsoever in your fish. Some people even add significant salt doses to freshwater tanks regularly; not enough that it becomes a salted or brackish tank even, but the addition of salt has benefits that some people like to utilise regularly. I recently added about a cupful of non iodized rock salt to a tank that is/was battling ich, and while it really made me nervous at the time, I could see an almost immediate effect on the fish in terms of liveliness and over the next few days colour even improved. It's said to help electrolyte loss and to maintain slime coat, etc. I'd not worry too much. Tap water has so much stuff in it that I reckon we'd possibly be horrified if we knew the full story!
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  • #3
Thanks for the help, do you think it will be ok the fill that tank when I have salt in the water softener tank I don't know how much salt is in it though.I didn't know people added salt to fresh water fish I was wonder about how much salt they add and are the only benefits the liveliness and colour?
  • #4
Can you smell the salt in the other tank? It's always good to know how much of anything is in your water but if if this is safe for your household then it will be a safe salt amount for your fish. I will copy what my box of API salt says for you:

"Electrolytes are essential for the uptake of oxygen and the release of carbon dioxide and ammonia through the gills. A lack of electrolytes may cause serious health problems. API aquarium salt, made from evaporated sea water,provides these essential electrolytes.
Benefits: provides essential electrolytes freshwater fish need to reach peak colouration and vitality. Improves gill function, reduces stress, facilitates osmoregulationand promotes disease recovery.

dose: add 1 rounded tablespoon for every 5 US gallons (20L) or 1/2 rounded teaspoon for every US gallon (4L) of aquarium water."

So it's a fair amount of salt! My 16OZ/454g treats up to 400 L of aquarium water.
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  • #5
Well I can't drink the salt water I have to either use a reverse osmosis filter (which wastes a lot of water) or buy water (which will cost a descent amount) so when you say safe for my house you mean I can drink it then it isn't safe (I think I can also smell it). I still don't think it will have as much salt as what you can put into your tank though. If I do decide to put salt into my tank I will have to figure out how much salt is in there from my water. Do you know a website that will tell me everything I need to know if I do decide to put salt into my tank? Also do you recommend putting salt into my tank?
  • #6
Many fish cannot tolerate salt. It is an antagonist that irritates the slime coat and gills. And if any have a cut, just imagine how salt feels when you have a cut.

Fish known to be sensitive to salt are catfish, angels and tetras. There are many others too.

I'd do some research. Water softeners based on an ion exchange with salt are not good for any aquariums.
  • #7
I'm extremely confused. You say you have a water softener, which utilizes salt as the method to soften the water. I don't know the inner workings of the things, but when I was a kid we had a water softener as you describe. It fed all the taps in the house and was neither harmful to us nor salt-saturated like sea water. Do you have something completely different from this? Does the water from your tap taste of salt when you drink it?

EDIT: Since I was curious, I looked up how water softeners work and here's a bit of info regarding how much salt one can expect to be in water softened by this method. I have no clue if this is harmful or not, but others may:

"Water softeners operate on a simple principle: Calcium and magnesium ions in the water switch places with more desirable ions, usually sodium. The exchange eliminates both of the problems of hard water because sodium doesn't precipitate out in pipes or react badly with soap. The amount of sodium this process adds to your water is quite small -- less than 12.5 milligrams per 8-ounce (237-milliliter) glass, well below the standard set by the Food and Drug Administration for "very low sodium" [sources: Shep, U.S. Food and Drug Administration]. If you have health concerns, discuss them with your doctor, or consider either using a different kind of softener or only softening wash water."

Taken from here: https://home.howstuffworks.com/question991.htm
  • #8
Salt is also especially bad for scale-less fish, and I don't think inverts enjoy it either.
  • #9
I don't know what kind of fish your keeping, but unless your fish are amazon river fish or fish that live in similar conditions you wouldn't want to use pure r/o water. You want trace minerals in your water. Do you not have a hose outside? Why would that water be softened? So if you got outside water source use that water. I use salt in my aquariums. In my African Cichlid tank I even use a little bit of marine salt to add trace elements.
  • #10
One option is to use potassium chloride in your water softener instead of sodium chloride. You should be able to find it at most places that sell water softener salt. It is more expensive but it is healthier and more environmentally friendly. Most people have too much sodium and not enough potassium in their diet and live plants will benefit from the potassium which is a plus both in your tanks and with any waste water that goes down the drain. Alternately you can just check to see if your water softener has a bypass valve that you can flip while you do your water changes.
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  • #11
sorry for my long reply but after I have read your replys I have decided to buy some water just to be sure my fish would be ok and I have been busy getting my tank set up.

@ mawelch74

My water won't hurt me if I drink it a little bit but if I drink it all the time it would start to be bad for me because I will be getting a lot of salt. My water also tastes a little salty.

@ flyinggogo

I do have an outside hose but it has bacteria in the water, it has coliforms in it and it might have e colI in it. I plan to fill my tank up with this water after I boil it (from evaporation and part water changes) the reason I didn't to this to start with is because it would take forever.

@ Ryan1824

I put a lot of thought into potassium chloride but I live in a small town so I couldn't find it that easily, also I would have to convince my dad to buy it (because I couldn't afford it) and my dad would not go for it

again thanks for all and I am really sorry I didn't replay sooner. x

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