So what in the world would SALT have to do with your freshwater goldies and koi?

Actually it’s a very interesting application that has experienced ponders in constant debate over it’s attributes in regards to helping their fish.

Have you ever walked into PETCO on fish delivery day and noticed in all the tanks there is a clear cup with dissolving chunks of salt ? If you watch close,.. as the salt dissolves you can almost see it wafting in the current like mist.

So why would you put salt in freshwater?  Salt has long been used with fish to help in dealing with sickness, or as a preventative measure before illness sets in. In the PETCO situation, they are trying to ease the stress the fish have endured during shipping. The salt helps the fish develop a thicker slime coat, which in turn can help the fish ward off nasty parasites and bacteria in the water that otherwise would find their stressed immune system a invitation for intrusion.

Fish (koi for example) must maintain their body fluids at approximately 0.9% salt content. So there is some minimum required amount of salt in the pond water for the fish to survive. But 0.05% is enough, even 0.03% is probably enough. Water from municipal sources normally have this amount.

Salt can also help to ward of nitrite spikes that some notice when spring comes around or when starting to cycle a new pond or quarantine tank.

Salt then seems to be a valuable asset when it comes to your fishes health, but is highly debated.

First off, treating one’s entire pond can be tricky. You want to treat the water, but not kill the plants. Plants begin to suffer at .3% and start to yellow. More sensitive plants like water hyacinth and water lettuce start to die at levels of salt lower than that.

Also, some believe keeping a high salt concentration over time actually negates it’s illness fighting purpose. The nastiest in the water have time to adapt and then become immune to the higher salinity.

Most tend to agree that having a separate quarantine tank is the best route to go. No plants to worry about. A smaller more manageable environment where you can single out the sick fish and treat them accordingly.

Now salt is not the miracle cure against all ailments. It is know to help ward off : ich, chilodinella, costia, trichodina. Parasites not effected by salt treatments are : flukes, anchor worm and fish lice.

For more info try this link to learn more on parasites and salt treatment CLICK HERE

So what type of salt to you need ?

Buying the pet store salt is not cost effective at all when your pond is thousands of gallons.

You also can use water softener salt sold at you hardware stores...just make sure they don't have additives and are pure salt. Table salt won't hurt too much as long as there aren't any anti-caking additives in it.
Pure salt with no additives.

Rock salt has a lot of other minerals in it, which typically is good for the fish provided it does not get too hard. I have used Solar dried water softened salt by the 60 lb. bag for about $5 bucks at Home Depot.

How much do I need per gallon of water ? --- about 8lbs per 1000 gallons.

Below is some excellent info from Lynn.

“Calculations based on pond dimension are very inaccurate, so the best bet is to gradually bring up the salt over 3-4 days. Get a salt test kit that is designed for freshwater. You will need to count drops added for a color change. If you know where the salinity level starts, and are careful about weighing the exact amount of salt added, you can calculate the actual pond volume by knowing how much the salinity changes.
I don't mind using salt in hospital on quarantine tanks, but avoid adding it to ponds. I wouldn't push the pond above 0.1%, if it were in my yard. If you do bring it all the way up to 0.3% you shouldn't keep it that high for more than 3-4 weeks. After that you will need to do two 50% water changes to bring it down below 0.1%. That is a heck of allot of water to dump and replace, and may throw the filter system out of balance.

You should be able to order a salt test kit online. I have both a Pond Care Salt Level kit (made by Aquarium Pharmaceuticals) and the KoiMedic salt meter (because I got tired of counting drops while trying to balance three overstocked quarantine tanks - nitrites were sky-high so I needed to keep salt levels up while doing water changes every 2 days). The test kit runs $5-8 online. You may be able to find it at a local fish shop, but I would call first. Hydrometers and marine salt level testers aren't accurate for low levels of salt, so make sure the kit you get measures in the range of 0.1-0.6%.”

Armed with this info, you can come to your own conclusion on the application of salt and your pond. Goodluck… and be sure to save some of that salt for your french fries ;)