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Steve,

I borrowed the following from KoiVet. It is a post I made on salt facts and myths and it might be good info for consumption or debate.. Enjoy..

Salt Stories...

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I really like talking about salt... almost as much as fungus and post-morts... so, here are somethings that we know as FACT about salt use...

1. Table salt..normal old iodized salt.. will not hurt your fish. Period. The old theory was that the iodine would hurt the filter... not true.. we tested this and proved it would not at concentrations to .6% over prolonged periods of time.

2. The primary reason we should not use table salt is the cost....MCA is absolutely right about this... but for aquarium, bath, and small qt-tank use... iodized salt is just fine.

3. Any salt with anti-caking agents in it is just bad. Ms Diva is spot on about the granular problems with some of the anti-caking agent. YPS (yellow prussate of sodium) when exposed to UV (sunlight) breaks down to a cyanide-related compound (do I have this right, Roddy?).

4. Most Kosher salts are bad..bad..bad.. they have other additives that make their use unattractive to fish (like YPS).

5. Places like Home Depot, Lowe's, Giant Foods, etc all have the water softener salt... 40 pounds = $6 or so. This is 99.7% pure salt and says so right on the bag. Sure, you need to work with it a bit, like dissolve it before adding it to the pond, but for large applications, it is the only thing that makes sense.

6. Sea salt, aquarium salt, and all of those other fancy pet-store salts are just WAY over-priced natural salt products. The type of salt called "sea" salt is just dried up sea water scraped into a bottle. The good thing about it is that there are lots of minerals in the water... but freshwater fish on a good diet will get the same effect from their food. Let's see? 69 cents for a pound of Morton Salt (iodized or not)??? $29.50 for a couple of pounds of "sea" salt?? The only time one should consider using sea salts is for marine tanks.

7. What koi really need is the chloride part of the salt compound. Ms Diva is right again (she usually is..) that potassium chloride and calcium chloride will provide the same chloride benefits but there is a price to pay for this. Koi and goldfish require exceptionally low levels of potassium and calcium in their physiological diets as compared to sodium (sodium chloride is table salt) so by trying to up your "salt" level with KCl or CaCL, you might inadvertantely hurt your fish with an overdose of potassium or calcium.. not impossible to do. In extreme ulcer cases, I will use a carefully measured combo of NaCL, KCL, and CaCL in the q-tank water to bring the electrolyte levels up in the fish as an open wound ulcer will "leak" electrolytes and the fish needs them back. This practice roughly equates to the use of Ringer's Lactate on humans in trauma cases. Gatorade is supposed to do the same thing but don't use it on your fish.

Primarily we use salt for two reasons: kill parasites and "smooth" out the fish's physiological balance through improving its osmoregulation process (which is managed by chloride). Fish use chloride to process waste through the kidneys, including excess water (freshwater fish do not drink water and do not like excess water). This is why in dropsy cases I recommend a .6% salt bath as the first step for stable fish to see if we can jump start the osmo process and have the fish expel the excess fluid all by itself.

And fish have special structures in their gills called " chloride pumps" that pull the chloride out of the water. This is part of the osmo process and the theory is that by us adding more chloride ions to the water, we reduce the fish's activity to "pump" it in. With osmoregulation, we know that the flow of "salt" ions is from lower concentrations (hypotonic) to higher concentrations (hypertonic). What this means is that because the fish has to maintain a .9% blood salt level to have all of its parts work right, it needs to "pump" chloride ions from the water into its blood stream and this requires energy to do this. So, as we increase the chloride levels of the water, we reduce the amount of energy the fish uses to pump in the chloride ions. This equals less stress.

Can you add too much salt?? The answer is yes, you can. The blood salt (chloride) level of koi and goldfish, like humans, is .9%. The chloride level of natural water is in the .03 to .1% range depending on where you live. So, you can see in natural conditions, the flow of ions is from the lower water concentration to the higher body concentration. And salt levels up to .8% will allow the freshwater fish's physiological processes to work fine. But when the water salt levels hit .9% and higher, the process starts to reverse and the salts are pulled out of the fish. You can even say that you can dehydrate a freshwater fish in water with salt levels above .9%.

Now, to Gerald's question...(took a long time, huh, GW?)... koi and goldfish will tolerate salt levels up to .8% just fine over extended periods of time (more or less), physiologically speaking. But increased salt levels (let's say over .3%) start to really irritate the fish and this causes increased mucous production and over time, a whole different set of problems. I am sure that many of you have read where prolonged salt exposure to levels up to .8% have been used by some koi keepers to fight off persistent parasites, but I gotta tell you, this is not to be tried at home as in fact, it can be dangerous. And if you have to fight parasites at .8% or higher, gee, there are better ways to do this than completely terrorizing the osmo system of a fish. Other than an occassional .6% bath for medicinal purposes, I would never use a higher level of salt for anything.

So, don't you wish that you had paid attention in high school biology class?? Salt is just too important to freshwater fish to not understand how it works and what it does. For those no-believers, if you want to try a nasty experiment, place a fish in distilled water and watch what happens... but do not walk away as this fish will start to deteriorate in a hurry without chloride in the water.

Final thought.... the chloride levels of our source water are more than enough to sustain the health of our fish... but measure the salt level of your source water just so that you know. And only use more salt in the water when you absolutely need to. Maintaining a higher than natural salt level is just not the best idea we have come up with lately.

Enough on salt??

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