In This Chapter
- Understanding the basics of stress
- Recognizing stress in fish
- Identifying the causes and lowering your koi’s stress (but not necessarily yours)
Stress is an unavoidable part of
life for any living creature. It’s simply a reaction to something uncomfortable
or new, which translates at first blush to possibly dangerous. A
creature’s avoidance reaction is a lifesaving gesture; fish in the wild simply
swim away from the perceived problem or anxiety source. But koi under our care
can’t leap out and go searching for greener pastures, so to speak. If ammonia
levels in the pond are too high, those fish are stuck. And being stuck topples
their anxiety into stress.
In this chapter, we help you
notice when your koi are stressed and help you understand the factors that most
often cause that stress. We also tell you how to alleviate or remove those
stressors. In most cases, fixing the problem just requires a bit of work and
forethought on your part.
How Can a Fish Possibly Feel Stress?
Human stress has two sides —
emotional and physical. Although it’s difficult for us to understand the
emotional life of a koi, or any other animal for that matter, the physical
aspects of stress operate very similarly in both humans and animals. Basically,
when an animal perceives a dangerous or disturbing situation, his body releases
a variety of chemical messengers to help deal with the problem (enter the fight
or flight reaction). The threatened creature is physically prepared by his
various hormones and chemical messengers to take appropriate action in the form
of defense or escape. A number of bodily functions are affected — eyesight
sharpens,
Although useful in crisis
situations, the stress chemicals cause severe health problems if they are
released long term, especially if the animal can’t react appropriately — where,
for example, the koi’s body is being primed to swim quickly, but it can’t.
Another health issue is the fact that, in times of stress, the body shuts down
functions that aren’t essential to immediate survival. The most common areas
are digestion and reproduction, and, over time, these can be severely impaired.
Of even more concern is the
long-term effect on the immune system — animals under stress sicken and die
from ailments or micro-organisms that may normally be of little consequence. Stress
is one of the most serious aspects of fish health but isn’t well understood and
is easily overlooked. Providing your koi with a suitable, stress-free captive
environment is a vital step in ensuring their good health.
Signs Your Koi Are Stressing Out
Because koi aren’t exactly big
talkers, how on earth can they tell you anything, much less mention that
they’re stressed? You don’t always need words to detect stress.
Remember
A huge part of detecting stress is observance. You simply watch your fish and let their behavior tell you how they’re feeling.
The signs of illness in koi are
both specific and nonspecific. The nonspecific signs are behavioral, and the
specific indications are physical symptoms. The following examples are typical
stress behaviors and indications to watch for:
- Failing to snorkel near the surface when feeder is near
- Jumping
- Lying partially on its side
- Remaining near the bottom of the pond
- Rubbing against items in the pond, as if to dislodge something from the skin
- Staying by itself; not joining with others to feed
- Swimming lethargically or with a tighter, almost jerky rhythm
- Trying to hide under ledges or under waterfall outflows
Physical symptoms are changes in
appearance that often point to a specific disease. They include
- Clamped fins
- Fin damage
- Pale gills
- Raised scales
- Swollen areas of the body
- White spots on the body and gills
You can use mechanical ways to
find out whether the problem is with your pond or your fish’s health. For
example, you can test the water for ammonia levels, or you can net and bowl
your big Yamabuki (“yamabuki” is short for the Japanese term “Yamabuki Ogon”
and refers to koi that are bright yellow in color) and see whether its gill
covers have a problem (for a description of gill lice, see Chapter Spotting
and Treating Common Koi Ailments).
Sources of Stress and How to Fix Them
Pretty much all the stress that
koi experience is human-caused. This is one of those blanket statements that
points the finger of responsibility right at you, the koi owner. You put a pond
in and okayed the design and the filtration system. You selected the koi — and
the number of koi for the pond. And you decided to enter that 24-inch Shiro
Bekko (a white koi with black markings) in the next koi show.
The good news is that, when you
know your koi’s stressor, you can take steps to alleviate the problem.
Remember
All this responsibility may seem a bit daunting, but don’t let it weigh you down. Koi are too beautiful and too enjoyable to allow you to be discouraged, and most times, your koi are just fine as long as you provide them with adequate food and care. In this section, we look at what, specifically, causes stress in koi and how you can avoid or remedy stressful situations.
Water quality
The quality of your water (or
lack thereof) is the biggest source of potential stress for your koi. Day in,
day out, night in, night out, your koi breathe in water, extract oxygen, and
push the water back out. But in fish, gills have a dual role — in addition to
allowing for respiration, they are also excretory organs. As a result, fish
excrete ammonia across their gill surface and release it into the water. Therefore,
a water-quality test should be your first reaction to any abnormal behavior
(lethargy, rubbing, disinterest in food, and so forth) that your koi exhibit.
Water in a clean pond dilutes the
excreted ammonia, and then the bacteria in the biological filter (see Chapter Planning
Your Koi Pond) gobble it up. But in a dirty pond, or
a pond with a nonfunctioning biological filter, theammonia levels build up.
Ammonia levels increase after the koi have been fed, and they really go up when
koi are overfed. The higher the ammonia level in the pond, the more
difficulties your koi have trying to push their ammonia out across their gill
surface and in breathing in general.
In people, ammonia irritates lung
tissue. Irritated bronchioles can’t absorb oxygen or exchange carbon dioxide.
Fish have a similar reaction. Exposure to environmental ammonia makes the gill coverings
swell. The rate of water flow across the gill surface decreases as does the gas
exchange rate (the flow of oxygen into and carbon dioxide out of the body).
Your koi may try to dislodge this irritation by rubbing Preparing
for Your Koi’s Homecoming) and discover the high ammonia content, you may think your koi has parasites
(see Chapter Spotting
and Treating Common Koi Ailments).
Low oxygen levels
Check your pond’s dissolved
oxygen levels, although fish that can’t get enough oxygen from the water
generally will be at the water’s surface, gasping. While you’re trying to ID
the reason for the lower oxygen levels, add a compressor and a couple of big
airstones to your pond to make your koi more comfortable while you nail down the
cause of the problem. In addition to the airstones, do a partial water change
and add a trickle feature to your filter outflow. The trickle feature can be a
waterfall or a fountain, or you can let the water from the filter roll down a
flat surface before it enters the pond — anything to increase the surface area
exposed to the air. Now you can look for the cause of the problem.
Watch out for triggers you can’t control
You can be as vigilant as possible, but sometimes
happenings outside your control affect your water quality. For instance, it rains
after your neighbor fertilizes his lawn, so some of that fertilizer runs off into your
pond. Careful planning in the initial stages of pond construction — locating it away from an
area bordering on a neighbor’s lawn, for example — can go a long way in
preventing such problems. But don’t expect to be able to foresee everything. Plan as
best you can, but remain alert and be prepared to take emergency action when
necessary.
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The oxygen levels can be
depressed because of hot weather, pond additives such as potassium permanganate
or an algaecide like AlgaeFix, or too many koi in your pond.
Crowding
Koi don’t deal well with crowds
because a crowded pond affects water quality. All your tests may tell you your
pond’s water quality is within acceptable parameters, but if you have too many
koi in your pond, those fish are living in a narrow band of water quality. Anything
that decreases that water quality has an immediate effect on the fish. One
small change (for example, the weather gets hotter, causing the water to
contain less oxygen, or sudden cool weather causes the warmer lower layer of
water to rise, bringing with it fish waste that had settled to the pond’s
bottom) and suddenly all your fish are affected.
Tip
How do you avoid crowding your koi? Use our formula of 1 1⁄2 inches of koi per square foot of pond surface. A 9-x-9-foot pond has 81 square feet of surface area and can be home to a total of 80 inches of koi — or eight 10-inchers.
Remember
Keep in mind that these fish are going to grow at least 4 inches per fish per year. Now, a sensible person would just sell off a fish a year to keep the total inches to a reasonable level. But real koi nuts like us just build a bigger pond!
Moving your fish
Who doesn’t get stressed out by
the idea of a big move? Even the hardiest of souls gets a little rattled with
all the packing, unpacking, unfamiliar surroundings, and so on.
Again, your koi are no different.
Netting and moving your koi stresses them. When you move your fish, you’re
moving your fish literally into new waters. The pH is different, the water
temperature may be different, and the levels of dissolved gases (including oxygen
and ammonia) are different. Even the light levels are different, especially at
a new site.
A koi’s reaction to a move will
be influenced by many things, including the length of the process, the degree
of difference in the two environments, and the fish’s individual character.
Upon introduction to their new home, your koi may swim about quickly for a
short time, and then remain fairly still in deep water or under cover. This is
a normal reaction to stress, and should pass within a day or so. They will also
likely not eat for the first day or two. If they are not behaving normally
within two to three days, you should check your water quality and make
adjustments as necessary.
Moving your koi to a new place
with little or no stress is a fairly simple process, but not a fast one. If
you’re bringing in some new koi or moving them from an old pond to a newer,
bigger pond (koi ponds only get bigger), you need to acclimate your fish to the
new water. Follow these steps:
1. Add some of the new pond water to the water in the plastic bag or transport dish and then wait five minutes.
2. Test the water in the bag for ammonia and nitrite level, and check the temperature. Add some more water and wait again.
3. Repeat these steps until your test kit and thermometer show no difference between the two waters.
For more precautions when adding
new fish, see Chapter Preparing
for Your Koi’s Homecoming.
After your koi are in their new
digs, keep an eye on them for a few days, even if they’re by themselves in a
quarantine pond. The stress of the move makes them susceptible to almost
everything: particles floating around in the water, subclinical conditions, you
name it.
Tip
If at all possible, provide a darkened area for your new koi. Koi adjust better to change when they feel secure, and they feel secure in darkened areas. Some koi owners put their plastic koi bags — the ones used for shipping koi — into black plastic bags before the bag/koi combination goes into the shipping container, or styro. If your pond doesn’t have darker areas in the deepest portion, try to shade part of the pond to create a darker area.
Temperature extremes
Koi are very tolerant carp
temperature-wise. They can live in outdoor ponds in water temperatures of 36 to
85 degrees F. But keep in mind that the temperature in these ponds should
fluctuate slowly, giving the fish a chance to acclimate.
When the water’s too cold
Your pond thermometer should read
above 50 degrees. Much colder than that, and your water freezes — “Goodbye,
koi,” and “Hello, fish popsicle.”
Normally, semidormant koi in a
winterized pond between 36 and 50 degrees stay in motion, swimming very slowly
or pausing and remaining upright in the pond. In ponds where the water
temperature is above 50 degrees, koi move around more readily and feed. Koi
that are too cold are lethargic, lie at an angle on the bottom of the pond, and
don’t feed. If the water remains below 50 degrees for too long, they may die.
You can use several methods to
correct a too-cold pond, beginning with temporary quick fixes and moving toward
maintenance for getting through the whole winter in good shape:
- Make partial water changes, providing the temperature of the new water is warmer than the pond water. Don’t change more than 30 percent of the water and be sure to dechlorinate as you add the water.
- Add a pond heater. For a smaller pond (less than 1,000 gallons), you can use electric heating tubes. They look much like your standard aquarium heater, but are larger, more durable, and use more current.
You can also opt for a gas unit that’s part of the pond construction and hooks up to your filtering system.
- Cover the pond with a plastic tarp or an insulated pool cover (leave one corner uncovered to allow for gas exchange) to prevent heat loss. By monitoring the water’s temperature after the cover is in place, you should be able to adjust what parts of the pond are covered and how long the cover is in place.
Tip
Refer to Chapter Maintaining Your Pond for detailed information on how to winterize your pond.
When the pond’s too warm
If your pond thermometer reads
above 82 degrees, you don’t have much of a margin of safety. Your koi are
probably rolling near the water’s surface, gasping for oxygen.
One reason koi ponds need to be
at least 3 feet deep is for temperature stability. Ever notice how warm the
water in a kid’s 8- inch-high swimming pool gets on a summer’s day, especially
when the pool is in the sun? The deeper a koi pond is, the more stable its water
temperature can be. And with less direct sunlight, the koi pond can stay even
cooler.
Although koi are fine in water
that may reach 85 degrees, you’re pushing the envelope. Temps this warm stress
your koi because warm water holds less oxygen, which makes koi work harder to breathe.
This extra work makes koi sitting ducks, as the saying goes, if one of them
gets a scrape or if the ammonia levels rise.
Tip
To cool your pond immediately, add cold water to your pond (usually, the temperature of the water as it leaves the tap is suitable). Again, add no more than 30 percent of the pond volume, and dechlorinate as you add the water.
If a too-warm pond is a chronic
problem for you, try shading part of or the entire pond with woven bamboo
screening. You can use bamboo window shades (available in home improvement
stores) or the woven shade cloth that gardeners use to shield plants from the
sun. See Chapter Building
Your Pond for more on landscaping the pond.
Other potential causes
Koi may indicate their discomfort
by jumping. If the ammonia and nitrite levels in the water are okay, there has
to be another reason for the acrobatics.
Do you have a submersible pump?
Submersibles have been known to short-circuit, and when this happens, your fish
are going to feel it. Don’t bother to
get the pump fixed; you and your koi are betteroff if you replace the
submersible with an in-line pump.
Are your koi new to the pond? Koi may jump if the pond is new to them. Sometimes differing water chemistry values, although acceptable, are different enough from what the koi is used to, and the fish feels, well, jumpy. Adding some koi tunnels on the bottom of the pond or some floating pieces of Styrofoam to the pond will give them a place of refuge and increase their security level.
by R.D.Bartlett and Patricia Bartlett
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