A number of bacteria are associated with finrot, lesions and internal hemorrhaging, notably Aeromonas and Pseudomonas. Ulcers usually start at the site of an injury, the bacteria then infect it causing further damage, and fungal infection can also occur.
Such holes result in osmoregulatory problems, leading to damaged kidneys and death if not treated. It is worth adding a weak salt solution to the pond as well as anti bacterial remedy, a concentration of 3gm per litter will help to restore the osmotic balance and reduce strain on the kidneys (make sure that the salt is fully dissolved before you add it to the pond).
Finrot is easily noticeable, the fins and/or tail look chewed and are red at the edges. Secondary bacterial and fungal infections can develop.
Koi & Pond Tip of the Day January 7th, 2009
NEVER install an air pump BELOW water level! (Unless you install a check valve in the line!) If at any time your power supply to your air pump is interrupted, water will back siphon down the delivery tube and flood the pump workings, rendering the pump inoperative.
