Bagging transporting koi and goldfish

When did you last attend or witness an awards ceremony? Your child’s sports day perhaps or the OSCARS or BAFTAS on TV?

The edited highlights of the televised awards generally show the most prestigious categories receiving their awards followed shortly by the winner’s thanks and acknowledgements for the different people or events that made ‘all this possible’. Tributes may vary from the ordinary (director, author, spouse etc) to the more surprising such as their mother and father for conceiving them, acknowledging that without them, quite literally, they wouldn’t be stood on that stage today.

In a similar way, the enjoyment and fulfilment that we gain from koi has only been made possible by the characteristics of the koi themselves.

Which characteristics would you list as those that have made koi keeping what it is today?

Their colouration


Potential for growth (and their ability to fulfil that potential – good old Chagois)

Their domestication

Becoming tame and conditioned to feeding and handling

Developing from a fish into a pet

Well all of the above would be at the top of my list, but I would also have to add a number of additional ‘unsung’ attributes that perhaps we are in danger of taking for granted.

Yet (and in true Hollywood style) if it were not for these other ‘hidden’ attributes, koi keeping would not resemble the thriving and dynamic hobby that it is today.

Koi are still carp

I’m referring to a koi’s ability to tolerate being transported for hours, confined in a plastic bag for many hours, with all that means for their physiology. Our hobby would at best struggle and at worst, not exist at all, if koi shared the same physiology of say a trout or a salmon.

If either of these species were bagged, handled and transported in the same conditions as our koi, for many hours at a time between Japan and the UK, they would not arrive alive. This ability of koi that lies at the heart of the koi hobby (which depends on the vast import/export business that is the koi industry) surely adds to the enigma of koi.

Quite paradoxically, koi require the best conditions we can provide for them in our ponds and yet they can tolerate conditions during their transport that may kill other species. So what is exactly going on?

Koi have been selected over many generations to exhibit the most desirable colours, patterns and body shape, where koi breeders have tried and succeeded in removing the dull carp from the koi’s vibrant livery. To a certain degree, their physiology has also been affected, but inside, they are still essentially carp in that they share similar traits with their hardier ancestors. Thank goodness they do, otherwise they would not tolerate the rigours of export.

Koi still retain their physiology that makes them adapted for their silty, still water environment, something we exploit every time koi are transported in the confines of a plastic bag. Compared to other species, koi have a low demand for oxygen and can tolerate a low dissolved oxygen concentration. Anyone who has had the opportunity of harvesting koi from a mud pond soon acknowledges how tolerant koi are of low dissolved oxygen, particularly when koi that may have been lying for hours in the silt on the bottom of a drained clay pond can be picked up apparently no worse for wear. Their innate ability to tolerate such conditions brings them through that experience.

Hundreds of years ago, well before the days of tanks, vats, bags and aerations, brood carp would have been carried for miles between ponds wrapped in moist linen and carried in ‘carp sacks’. A practice that spread both the reputation of the carp as a resilient food fish and the species itself.

Koi physiology is also tolerant of a short term deterioration in water quality, something that is particularly evident during spawning time. Adapted to life in natural, lowland lakes and waters, where rapid changes in water quality can occur very quickly.

During the warmer months, when carp will gather in warmer shallower water to spawn, literally millions of eggs will be released with only a small percentage being fertilised. The remainder will breakdown, representing a substantial and rapid deposit of protein that will begin to be broken down, causing a rapid rise in ammonia, nitrite and a drop in DO.

Although this represents a threat to koi, in the short term they have the ability to tolerate such poor extremes in ammonia, again something that we exploit each time koi are transported over long distances in bags.

What Happens inside a bag.

Standard practice when bagging up koi for export or by a dealer after a sale is to fill the bag with approximately 1/5 water and 4/5 oxygen by volume. Sufficient water to keep the koi adequately submerged with most space being taken up by essential oxygen. Furthermore, when koi are exported, it makes economic sense to keep the volume of water to a minimum. The koi trade imports some of the most expensive water into the UK when you consider how much they have paid to import it! The less water, the more economic the freight, but there is a fine balance that experienced packers have perfected over many years.

As soon as koi are bagged up, they become stressed. It is inevitable and unavoidable. The act of handling, netting, and the introduction into a confined environment causes a stress response in koi.

Typically, koi will release a number of hormones that start a chain-reaction within their physiology. The role of the stress hormones is to mobilise energy very rapidly so that koi can take flight and escape the stressor.

Unfortunately, there are undesirable side-effects that can have serious implications for koi health, especially if the stress is prolonged.

Side effects include:

A rapid increase in blood sugar levels

Increased heart rate, blood flow and oxygen demand

Increased susceptibility to disease

Two notable types of hormone that are released in response to stress are adrenalin and corticosteroids.

Adrenalin causes the increase in heart rate, mobilising energy into the blood so that koi can, if given the opportunity, make its escape by using energy rapidly. This will also cause blood to be diverted to the muscles and flanks of the fish, ready to supply both oxygen and energy for when they are required. The excessive supply of blood to the muscles also causes capillaries in the skin to dilate, becoming visible to the naked eye and making white skin appear pink. In fact, the extent to which these capillaries are visible can be taken as a guide to the levels of adrenalin and hence stress that the koi is experiencing.

Corticosteroids have the undesirable side effect of making koi more susceptible to attack from pathogenic organisms (bacteria, viruses, parasites etc) In fact, tests have shown that unstressed fish can be made more open to infection if they are injected with these hormones.

Careful bagging will ensure that koi have sufficient oxygen for their journey. The oxygen they take in will be exchanged for carbon dioxide. In a larger volume of water that is open to the atmosphere, excess carbon dioxide would be released into the atmosphere. In a bag, it can accumulate, causing two knock-on effects.

A drop in pH, as the carbon dioxide forms a mild carbonic acid in the bag

An increase in respiration rate. Fish are stimulated to breath at a faster rate in response to a build up of carbon dioxide (rather than a drop in oxygen) in the blood. If there is a build up of carbon dioxide in the water, then koi will struggle to release excess carbon dioxide from their blood, causing them to breath at a faster rate.

A similar phenomenon will occur when ammonia builds up in the bag. Koi rely on a diffusion gradient between their blood and the pond water. If there is a build up of ammonia in the water, then koi are less able to release ammonia from their blood – causing it to build up and adding further to their stress.

Counter Measures to reduce stress when transporting koi.

Keep bags as cool as possible as this will slow down koi metabolism and respiration rates.

Keep bags boxed up to reduce the stress experienced by koi when light bombards them from every angle.

During lengthy journeys, a mild sedative has been known to be effective at reducing the respiration rates of fish.

The addition of a mild antibacterial treatment (such as Elbagin) into the bag during transportation can have a desired preventative effect against the threat of disease.

In summary, when considering the potential problems that koi can experience during bagging or transportation, their ability to tolerate such conditions is a testimony to their physiology and adaptation for overcoming periods of short term stress.

Nevertheless, we should not take a cavalier attitude with regard to their health during transport and should always ensure that suitable quarantine or recuperative facilities are provided. Considering the ordeal that many koi may experience, we owe them a time of recovery and readjustment, and will be rewarded by healthier and more vibrant koi.

Kill blanketweed and string algae.