To salt or not to salt?

To salt or not to salt?

By Angela Beckx

There are both pros and cons to using non iodated sea salt in koi ponds; some koi keepers feel it is very beneficial while others are strongly against it. Non iodated salt is very affordable and is widely available, so it is often recommended. In my opinion, salt is most useful as a short-term treatment, or a treatment to be used in quarantine procedures. Let’s look at some of the benefits of using salt as well as some of the problems it can cause.

The pros of using salt:

  • Salt promotes mucus flow on the skin of the koi, which helps protect the koi against harmful life forms like parasites, fungus and bacteria. The extra mucus makes it harder for them to infect the koi.
  • Salt is known to have mild bactericidal properties, which makes it very useful for controlling bacterial infections that are usually encountered in poorly maintained ponds. Salt can help work against many protozoan parasites, including costia, trichodina and chilodonella, as well as flukes and other ectoparasites.
  • Salt can also assist in osmoregulation problems caused by bacterial ulcers and help clear congested gills.
  • Salty water is believed to relax koi and relieve the stress caused by osmosis.
  • Salt is safer than many other treatments that are added to pond water and will not adversely affect the biological filtration in koi ponds as long as the salt is added to the water in the pond and not the water in the filter section. (If salt is added directly to the filter the sudden rise in the salinity kills the beneficial bacteria in the bio-filter.)

The negatives of using salt:

  • Once you add salt to your pond water it remains in the water; it will not evaporate and your filter will not remove it. This means you need to keep detailed records of the dates that you add salt and the quantities. The recommended dose is 3 kg of non iodated salt per 1000 litres of pond water. I recommend buying a salt meter so that you can measure the salinity at any given time – without a meter it is very difficult to control salt concentrations.
  • If you have sick fish and they are not recovering after using salt then you will need to use a stronger medication. This is when using salt becomes a problem because it can react negatively with some of the other treatments: both malachite green and formalin, two common medications, do not mix well with salt.
  • Using salt can be harmful to your pond plants – it can cause them to turn yellow and even kill them. I recommend removing the plants, especially the free-floating ones, before commencing a salt treatment.
  • Salt can be corrosive; it can even cause corrosion in metallic features around your pond.
  • An overdose of salt reverses the osmotic pressure between the koi and the water and this can kill the koi. This happens because they release too much water and they die of dehydration.
  • If salt is added directly to a filter the sudden rise in the salinity kills the beneficial bacteria in the bio-filter.
  • If the salt concentration remains high for an extended period of time then certain pathogens can build up a resistance to it, making it ineffective for treating those illnesses in future.

Many experience koi keepers recommend these two ways to use salt when quarantining new koi.

Option A

Disinfect the koi by placing them in a salt dip for five minutes at a dosage of 1 kg of coarse salt to every 30 to 50 litres of water. Thereafter, move them to a quarantine pond filled with fresh water that has been de-chlorinated and is the same temperature and pH. Add an antibacterial medication at a low dose for one week, then add an anti-parasite treatment to reduce the parasite load. Leave the koi in quarantine for four weeks to make sure they are healthy before you introduce them to your main koi collection.

Option B

To eradicate salt-susceptible parasites set up a hospital or quarantine pond, using a separate pond or porta pool. Use an air pump and make sure lots of air is being pumped into the water (this is especially critical in summer time). Add salt at a rate of 3 kg per 1000 litres of water and leave the koi to swim in the salted pool for seven to 14days to eradicate the parasites.

If this article has piqued your interest and you are considering using salt then additional reading will be necessary. Apart from the information in the koi books I recommended in December 2009, it is well worth paying the following website a visit: {

Sources consulted:

Article written by Angela Beckx of Koi @ Jungle. Contact Angela on 031 2098781 or visit: Koi @ Jungle also stocks swimming pool products and equipment.

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