As the title says bacterial infections I will try to explain how it comes about and how to deal with it.
Bacterial problems stem from poor water maintenance normally a build up of muck somewhere in your pond system. A build up of muck will very quickly turn bad and will be a breeding ground for bad bacteria, these bacteria are called Anaerobic bacteria and can live and grow without any oxygen. One of the signs is a build up of Hydrogen Sulphide that makes your pond or filters smell like bad eggs though this is not always present.
This can be neutralized with a dose of PP (potassium permanganate) but you must find the underlying cause of this. Poor filter maintenance is the most common cause, stagnant soil in waterfalls, planters or vegetable filters (dead or dying vegetable matter) and dead or decaying blanket weed on the pond floor as well as decaying food and fish waste that will collect in it. Some filters have grids in the bottom this is a common collecting place also in a sieve or the bottom of any filter if not maintained regularly. Liners with folds can trap waste too.
So what I am saying is it’s all about keeping you entire system as clean as possible and doing regular water changes to keep your water as fresh as possible.
The typical signs on the Koi will be raised and infected scales, fin rot, mouth rot, ulcers, dropsy and in the later stages septicemia (blood poisoning). Cloromine T treatments will help to lower the bad bacteria levels but it must be remembered it will also lower the levels of good bacteria and may if your filters are not mature knock them back.
All the bacteria needs is an entry point into the Koi’s body,this could be a knock wound or parasites.
If the affected koi can be moved to a hospital tank (this must be a fully matured system with perfect water) with heat at 26 DG, salt at 0.3 % and three doses of Cloromine T this would help the Koi vastly. For dose rates on the treatments mentioned follow the instructions on the manufactures packaging.
For treating these infections have a look at the topics here http://forum.koimag.co.uk/tm.asp?m=413553
Here are some photos of bacterial infections.
Bad fin rot and a bacterial infection
Bacterial infection caused by the Koi sitting on the pond floor in winter
A servere bacterial infection that has entered the Koi’s body causing probable septicemia
This infection was caused by the koi flashing due to parasites