Please help, was difficult to notice with pump running 24/7... however closer inspection was horrifying. Also no behaviour differences from healthy fish.
https://s1008.photobucket.com/albums/af202/osadrian/Sick%20koi/?albumview=grid

Fin rot...... bad pond management..... Potassium Permanganate at 2.56g per 1000L or up to 3g per 1000L. Can buy from pharmacy. 3 to 4 treatments 2 to 3 days apart. Replace about +- 20% water after each treatment.
Check water parameters and correct. Water changes are critical, and by doing weekly water changes you will not get this problem. I had tropical fish and if you don’t look after the tank this illness will become a problem but can be rectified easily and they will survive

But also keep the next line in mind. Wayne had problems with bacteria: Take advice what can happen……..

‘’Last week I had a swap taken on one of my expensive imports that I did not want to loose. The swap was sent to path care and the result came in today.

My Koi are being affected by the Pseudomonas bacteria. Here is some info about the general strain http://en.wikipedia.org/wiki/Pseudomonas

My particular strain is immune to all medications except 2 antibiotics....and the one is no longer available.....so there is only one that will work.

Interesting enough these bacteria is so tuff that it can live in anti-septic solutions. Its outer wall of its cell is also very thick and it grows a bio film which helps to protect it which means that normal ant-bacterial medications like PP wont kill it.’’

Frightening isn’t it ………

Thanks, busy with treatment, will post results...

How long till I see results... and also indication when condition will be 100%... I know it's like asking , how long is a piece of string, but general indication will be great.

You do have a severe bacterial infection in your pond, and potassium will only work if the infection has not spread internally yet.

The first photo (red fish) indicates popeye which indicates Dropsy, and is a result of the bacterial infection. You can not really treat dropsy although some people say they had success with Acriflavine and salt.

The one Sanke has finrot, is developing an ulcer and the other one possibly has a tumor also. I agree with Marius that the best treatment is Potassium. The value of the fish does not justify anti biotic injections.

Do a whole course of PP treatment (4 or 5 treatments two days apart) and hope for the best. It might be too late. The finrot has developed quite far.

Also increase your salt levels to 4 kg/1000 liters. You also have to work on the primary cause for the infections, being water quality. Test your water for Ammonia and Nitrites on a regular basis and rectify, especially because you are doing a PP treatment.

Healing will take months, especially in winter months, but it also depends on your water conditions.

You should ideally treat in warm water to ensure quicker results if possible.