Adding salt to the water of a sick tank or quarantine tank can help sick or compromised Koi. In essence, it makes it easier for them to breathe, just the way supplemental oxygen helps people. To learn more about how salt reduces the osmotic pressure gradient, take K.O.I. #206 - Physiology - CLICK HERE for course description. Here's what Dr. Richmond Loh, the Fish Vet from Australia has to say about salt...
How often must I add salt to my aquarium – pond – fish tank?
Salt (sodium chloride, or NaCl) is useful for the health management of sick fish. In most cases, you’re maintaining salt level at 5g/L for most freshwater fish species.
Once added, salt doesn’t leave the system or evaporate.
So it’ll mean replenishing any that’s lost when conducting water changes.
On the contrary, salt levels rise if you’re simply replenishing the evaporated water (e.g. during summer)!
This means testing the salinity, and then calculating how much you need to add back.
Alternatively, it will be fairly safe if you add 3-4g of salt for every litre of water you’re changing.
Dr Richmond Loh
DipProjMgt, BSc, BVMS, MPhil (Pathology), MANZCVS (Aquatics& Pathobiology), CertAqV, NATA Signatory.
Aquatic Veterinarian & Veterinary Pathologist.
PERTH | MELBOURNE | SYDNEY | TOWNSVILLE | BRIBIE ISLAND.
THE FISH VET – AUSTRALIA.