Salt: The addition of 1/4oz/ gallon of salt to your hospital tank (not pond) will greatly help to reduce the osmotic stress on your Koi as a result of the injury. Where an ‘open wound’ from ulcerations & lesions occur, the exposed tissue will act as a semi-permeable membrane where the fish can gain water and loose salts.
In cases of extensive damage to the skin surfaces, be aware that there is a danger of you Koi taking on board a considerable quantity of ‘water’ and if left un-checked for a substantial period, it is likely to result in malfunction of the osmoregulation system and eventual failure of the ‘Bilge pump’ (i.e. the Kidneys which excrete a large amount of the water).
Where extensive skin tissue damage has occurred, we have increased the salt concentration in the hospital tank to to a maximum of about ¾ to 1 oz/ gallon but the Koi should not be left indefinitely at this level (1/ 2 weeks OK before reducing slowly); as they are a freshwater fish. The salt level should be altered in ¼ oz/ gallon increments per 24 hours. In addition, we have added mineralised clay to the tank to further increase the ‘density’ of the water, reducing osmosis and diffusion. Its mild bactericidal properties can also be beneficial.
Recently, our approach to ‘wound repairs’ has been to keep the water excellent (with very low salt, if any) and encourage ‘rapid sealing-over’ by a high temperature (25 deg.C)/ bags & bags of air/ Jacuzzi type of environment. The Koi are gently raised to the surface and scraped regularly for parasites. The initial ‘skinning’ can occur in about 48 hours but you need a relatively stress free & sterile environment to avoid encouraging pathogens and parasitic problems.
However, with practice, you will develop your own preferred methodology of dealing with the healing process.
Once a Koi has ‘got a bit unwell’, we have found in many instances that due to the greatly reduced resistance to invasion, there is a likelihood that Costia, a secondary parasite will appear. This very small parasite, identified by microscopy by its flickering and turning. It will create havoc with your Koi’s cardio- vascular system (in addition to the less important skin damage element) and will cause mortality if left un-checked. The addition of ½ oz/ gal of salt in the hospital tank will eradicate this problem.
In summarising salt as a therapeutic treatment, it has three properties which can be used with advantage at times:
- Reduces osmotic stress and helps in reducing ‘water in-take’ if this is likely to be a
- Good at keeping Costia away.
- Has mild bactericidal properties which can be beneficial.
The use of a salt as a medium/ long term bath will vary depending upon individual circumstances.
Remember that the salt you use should be of the ‘dishwasher’ variety without additives – ask your local Koi dealer for some if you are not too sure which type to buy.
Finally, always make a note of the amount of salt you have used in the tank. You will need to be able to assess the amount to put in during water changes in order to maintain the current concentration.
Useful Conversion: 1/2oz salt per gallon = 3 grams per litre = 0.3% salt level