Chapter 12 Koi Health Issues & Accidents
Koi health problems are usually linked to poor environmental conditions which have been referred to in earlier chapters however even in the best managed koi ponds some koi health issues may arise from time to time.
Spawning can sometimes be the cause of scale loss and fin damage as it can be a physically traumatic time for koi as the males drive the females to encourage them to release their eggs. Koi living in good water conditions usually heal without any intervention but it is not uncommon for minor bacterial problems to arise around the damaged areas.
The mucus and skin of a koi are first line defences and form part of the immune system against the relatively hostile environment of the pond water. Bacteria such as aeromonas and pseudomonas are always present and these opportunists can take advantage of the breech in the koi’s natural defences when mucus and scales are lost or damaged.
It is quite natural for koi to eat the eggs produced by spawning and this high protein food can produce high ammonia spikes followed by high nitrite levels in the pond water. The ammonia levels usually fall within a day or so but the nitrite takes longer for the filter to process as explained above. Ammonia and nitrite in the pond water will irritate the gills and skin of the resident koi and can often cause them to “flash” (rub themselves) against the pond side and pond bottom, removing mucus and sometimes scales.
At any time that damage is noticed it is wise to check the pond water parameters; nitrite removing bacteria are sensitive to any environmental changes and slow to build up their colonies if a sudden increase in nitrite occurs; this can happen when koi spawn.
If damage of any kind is noticed, keep a watchful eye on the koi to check that the area does not become inflamed as will happen if the damaged area becomes infected. If you are unsure of the state of the wound it is possible to sedate the koi and apply an anti bacterial/fungal topical dressing such as “WoundMed”.
To sedate a koi it must be netted and transferred, preferably using a “sock”, to a suitable sized bowl which contains pond water to which a sedative has been added in accordance with the directions given on the packaging. I use phenoxitol which itself has antibacterial properties and is safe in use. When the gills of the koi stop moving it is ready to be removed from the sedation bowl and examined.
Prepare a towel by soaking it in pond water; lay the koi on its side on this wet surface ready for examination. As a matter of course I always check the koi’s gills by carefully opening the gill covers and checking for colour, which should be a deep red colour resembling fresh liver. The rest of the koi can be checked over by looking its mouth and the base of the fins. These should be clean without sign of any redness associated with bacterial infections.
Now examine the area which is damaged or has scale loss; if it appears to be clean and without undue inflammation it should be dried using a tissue and a suitable topical dressing applied to seal the wound and offer some protection against water borne infections from bacteria and fungi.
If the wound appears red and inflamed the advice given in the following chapter “Wound Healing in Koi” may be followed.
Once the topical medication has dried the koi should be returned to the water where its gill movements will indicate that it is recovering from sedation. The koi may be held in its normal upright position at this time; if gill movement does not begin immediately the lower jaw may be pushed downwards several times to pump water across the gill membranes to aid fast recovery.
Other accidents can occur such as damage by predatory animals including Herons which stab the koi and often leave deep wounds with associated scale damage and loss.
Deep wounds may need special attention and the use of antibiotics but as a matter of course the wound should be tended to by removing any damaged scales, cleaned with hydrogen peroxide (3%) and a topical dressing applied.
Koi can sometimes jump out of the pond and after rolling about on the adjacent soil or patio, can suffer from severe mucus and scale loss. Do not despair for even if the koi appears dry to the touch they can often recover. It is important to get any such casualties back into the pond immediately; hold them in the water and resuscitate them in a similar manner to that used when reviving koi from sedation. Sometimes it is useful to hold the koi in a flow of pond water in the pond returns; water flowing through the gills will allow the uptake of oxygen and help to dispel any carbon dioxide and ammonia gases from the bloodstream.
Once the koi appears to be breathing normally again it can be beneficial to place it in a container with salt added to the water at 1 g/litre. This will help to reduce stress, allow the gills to clear any sticky mucus which could impair oxygen exchange
Koi do not normally jump out of the pond without a reason; the environmental conditions should be the first thing checked followed by a check for any parasites which may be causing some irritation to the koi.
The use of pond medications such as ChloramineT or Potassium Permanganate may be useful at these times to reduce the levels of infectious bacteria in the pond water. Specific treatments for parasites may be necessary if they are found to be present.
Normal and abnormal behaviour
All keepers soon become aware of the normal behaviour of their koi. Any individual koi which remains on its own and ceases to be a sociable shoal member should be watched carefully as these symptoms are often the first signs that all is not well with them.
At various stages of their growth koi shed their teeth which are located in the pharynx (pharyngeal teeth). Occasionally this can cause them to sulk and they can sometimes be seen shaking their heads from side to side possibly in order to expel the loose tooth which can sometimes be found on the pond floor. Sometimes koi keepers believe that parasites such as gill flukes are to blame for this behaviour but a koi which is seen doing this and then resumes its position in the shoal and behaves normally again is likely to be shedding a tooth!
Koi are naturally sociable animals and may well form bonds with some of their pond mates! Some koi are friendlier than others and will soon take food from their keeper’s hands whilst others are less friendly. Chagoi are reported to be the friendliest of koi however this is not always so and in my experience they are no friendlier than other varieties. Healthy koi kept in good water conditions soon become quite friendly and readily take food from the owner’s hand.
In my experience koi added to a pond where the inhabitants are quite tame soon become tame themselves; perhaps the signals of the shoal indicate that all is well. Similarly if a friendly koi is added to a collection which do not hand feed they usually encourage the existing inhabitants to hand feed too. It seems likely that fish in general do communicate; watching shoals of fish move in perfect unison tends to indicate this.
When I add new koi to a communal pond I notice that these “wild” koi quickly settle in and hand feed as readily as the originals.
Although they do not show hierarchy like some animals, they do seem to be conscious of shoal members who are not acting normally such as when a sedated koi is returned to the pond and it lies on its side on the pond bottom. At these times it is not uncommon for the shoal to nudge the sedated koi in an apparent means of encouraging the koi to resume its place with them.
Sick koi are usually left on their own; perhaps they have an inherent sense that all is not well and they distance themselves from what could be an infectious source?
Sometimes, especially after feeding koi can be seen mouth to mouth; at such times they are not showing classical human affection, rather they are trying to suck pellets from each others mouths!