In This Chapter
- Playing (koi) doctor
- Getting a handle on koi exams
- Caring for the mild trauma cases
- Recognizing and controlling parasites
- Caring for bacterial infections
- Addressing fungal infections
- Knowing all you can about viral infections
- Setting up the hospital tank
- Grasping the finer points of koi first-aid
This is the chapter we hope you
never need, but if your koi get sick, this information can help you figure out
the problem and its remedy. Our goal is to help you avoid the loss of even one
koi.
Koi can seem delicate when you
realize everything that can make them sick — the quick change of their pond’s
temperature, below par water quality, new koi that haven’t gone through a
30-day quarantine period, and so on.
The amazing part is that after
you know the cause and make a few corrections, the koi get well (if the
condition hasn’t gone on too long). Usually. We add the qualifier because koi
with koi herpes virus (KHV) don’t get well. This virus has no treatment and the
disease is highly contagious to other koi.
Everyone understands that when an
expensive koi gets sick, the effort to save that koi is worthwhile. But we
think all koi, even those that aren’t drop-dead gorgeous, deserve the very same
effort. So in this chapter, we give you all you need to recognize a
Empowering You, Because Koi Vets Are Few
Koi vets in the United States are
few and far between. In fact, koi vets are rare around the world.
Part of the reason for the low
number is the low number of koi-keepers (compared to dog and cat owners, for
example). And part of the reason is that people don’t know about koi. Think
about it. Koi don’t need to be walked, they don’t need shots, and they don’t bring
home fleas. What’s not to love about koi?
Remember
The demand for small-animal care is a lot greater than the demand for koi medical care, so veterinary colleges spend very little time offering courses in fish care of any type. Veterinarians learn koi-keeping details after graduation, from other veterinarians, advanced courses, books, koi-keepers, and koi breeders.
Don’t fret, though. This chapter
provides a load of guidance to help you diagnose and treat your sick koi. If
you also want to seek professional guidance, consult one or more of the
following sources:
- Your local veterinarian: Although only a dozen or so koi veterinarians practice in the United States, almost every veterinarian can help when problems crop up in your pond.
- Fish farms and aquariums: Tropical-fish farms in Florida often have a veterinarian on staff. Commercial aquariums, like the Tennessee Aquarium, employ their own veterinarian. These veterinarians may be able to answer your questions.
- Koi health specialists: The lack of formal veterinary training has led to another specialization, koi health specialist. Any serious hobbyist can take this certificate program. The United States has two programs: one is operated by the Mid-Atlantic Koi Club (MAKC, www.makc.com) and the other by the American Koi Association.
- Other koi fanciers: Talk to other koi-keepers because most likely they’ve been there, done that, and they’re great at sharing their expertise.
Search online through the
Mid-Atlantic Koi Club (see earlier bullet) or the Associated Koi Clubs of
America Web sites for contact information. If you’re not handy with the Web,
ask your local public librarian to help you make the search.
Tip
Before you contact someone about your koi’s ailment, be prepared to answer the questions that you wil be asked:
- How old is your fish? (Younger koi are more susceptible to KHV and spring viremia of carp [SVC] viruses.)
- How long have you had the fish?
- When did you notice that something was wrong?
- Is the fish eating?
- What size is your pond?
- How many fish are in it?
- What are your water chemistry values?
- What type of filtration do you use?
- Have you added any new fish to the pond?
- Has the fish been treated with any medications?
- How is the fish acting?
Taking a Close Look: The Do-It-Yourself Koi Exam
The diagnosis of koi ailments is
a tricky business, and serious problems are best left to a veterinarian.
However, it is, in some respects, an art as well as a science, and therefore as
you gain experience you may learn to recognize certain problems.
Catching your koi
In order to closely examine your
koi, you will first need to contain it within a small place. This can be quite
difficult or easy, depending upon the size of your pond, the koi’s temperament
and state of health, and your own skill. You may want to practice netting and bowling
your koi when your fish are healthy, so that you will be prepared in the event
a fish falls ill.
Examining your sickly fish
Signs of injury and disease in
koi range from very obvious to quite subtle. A comprehensive physical exam, as
described in this section, offers the best chance of detecting your koi’s
particular ailment.
Surveying his overall appearance
Although netting and bowling your
koi adds to its stress, you need to examine him to identify the problem and
treat the illness. Once he’s in the bowl:
1. Look for external parasites.
(See the section on parasites later in this chapter to help you ID and deal with them.)
2. Look for any open wounds, or abnormal appearance to the body or fins.
3. Lift your koi out of the water using your wetted hands, and check for lesions or open wounds on his underside.
4. Put him back in the bowl when you’re done, and gently pour out most of the water in the bowl so you can take a swab or a scraping.
Taking a swab or scrape
Taking a swab is not as traumatic
as it sounds. Follow these steps:
1. Drag and roll a wet cotton swab over the gill covers, or along the base of the dorsal fin, or along the base of the tail to gather some of the mucous that coats the fish’s body.
Remember
Always swab from the head to the tail, working in the direction the scales grow.
2. Roll the swab along the surface of a microscope slide, add a drop of pond water and a cover slip, and examine the mucous (after it’s on a slide, it’s called a smear) under a microscope.
As an alternative, your veterinarian may furnish you with the swab, a tube, and a mailer envelope to send the specimen to a lab to identify possible bacteria.
If the swab is inconclusive, or
if external parasites are suspected, your veterinarian may suggest the slightly
more invasive skin scrape. To take a skin scrape, do the following:
1. Scrape a blunt object, like a glass slide, along the body to gather some of the mucous.
This step is the same as Step 1 for the swab, but because you need to apply a bit more pressure, have someone hold the fish while you gently but firmly scrape off some mucous.
Remember
Always scrape in the direction of the scales; never run against them. Because the scraping peels off external parasites between the scales, scrape where you think your koi is most stressed, near the gills or near the fins, for instance.
2. Add a droplet of pond water and then a cover slide. You’re ready to examine the scraping under the microscope.
Inspecting the small stuff: Enter, the microscope
When you first look at a smear or
a scrape under the microscope, you may feel as if you’re in uncharted
territory. The micro-organisms that you might encounter exhibit a bewildering
array of shapes, with many appearing to be straight out of a horror movie.
However, with a bit of experience, you may be able to at least identify some of
them in a general way, and this can help point the way toward an effective
treatment.
- Compare what you see under the microscope with the drawings in this book. (See those illustrations throughout this chapter.)
- Go online for more information on koi parasites. (Check out www.koicarp.net or search under koi parasites.)
- Ask a more experienced koi-keeper to guide you through this smear-making and slide examination process that we describe in the previous section.
You really will get better with
practice.
Dealing with Mild Traumatic Injuries
Koi encounter few traumas in the
pond; they just don’t have many opportunities bang up against something.
Nonetheless, they still manage to get into a few scrapes.
Some injuries are seasonal and
relatively minor. In spring, for instance, actively breeding koi tend to lose
scales as part of the jostling during courtship. The female in particular may
lose patches of scales and have a split fin or two. The only necessary
treatment is a week or two of R&R in the warm waters of a hospital tank and
away from other koi.
Three-tenths of a percent salt
solution (three pounds per 100 gallons of water in your pond) helps the fins
heal, but see “Fin rot” in this chapter for more information on this condition.
As fungus can take hold on damaged fins or skin, keep an eye on these koi while
the fins heal.
Kinked spine also seems
trauma-linked, but it can be the result of a poor diet (very obvious in
younger, fast-growing koi), exposure to high levels of organophosphate insecticides
(as a human, you don’t really want these near you either), or electrocution.
Many times the damage to the spine is permanent and euthanasia is the logical
answer. Koi owners who can’t bear the thought of killing one of their favorites
usually hand feed the affected koi.
Electrocution can occur wherever
there’s electricity; when you combine water and electricity, the chances of
something going amiss only escalate. Electrocution fries the nerve axons,
causing some muscles to become permanently contracted and other muscles to
become spasmodic. Because muscle control is gone, the electrocuted koi swim in
a jerky fashion. When the fish are challenged or stressed, the swimming motions
can become even more erratic until the fish loses the ability to swim
altogether. An electrocuted fish drops weight — partly because he uses so much
of his energy just trying to swim, but mostly because he can’t compete with the
other koi for food.
The Most Famous Parasites of All
Parasites are a common problem
for all fish. When you mention parasites with koi, you generally mean the
external variety. These parasites are always present and easily pass from one
fish to another. The eggs or cysts may remain inactive and undetected until the
weather warms up, but then the birds sing, flowers bud — and all of a sudden
your koi are a-bloom with external parasites.
Remember
The problem with a parasitic infestation — other than obviously damaging your fish through the actions of the parasites themselves (feeding on blood and skin tissue, for example) and killing your appetite for cheese rollatini big-time — is that the condition sets up your fish for secondary bacterial infections.
Tip
The good news about parasites (and we do have some) is that a salt treatment kills many of them. Sometimes you have to add a secondary treatment, but salt’s your number-one choice for Ich, Costia, and Chilodonella. (Check out more about these conditions and their treatments later in this section.)
Anchor worms
An anchor worm (see Figure 13-1)
is a crustacean that looks like a worm. The females embed themselves in the
skin of a koi, usually near the gills, around the eyes, on the fins, and on the
base of the fins. A scraping and examination under a microscope can help you ID
the varmint. Adult anchor worms are just under 1⁄4-inch to 1⁄2-inch long and
look like brown or black strands standing out from the koi’s body. The site of
attachment is usually inflamed, and the involved scales may be raised up a bit
from their normal position. Young anchor worms look like white dots on the skin
of the koi.
Figure 13-1: An anchor
worm, alone and attacking a koi.
When you find them
Anchor worms are inactive during
the winter but become active when the water warms to the upper 50s. Suddenly
all your koi have anchor worms, and the fish may flash and leap in an attempt
to dislodge the little pests. But the bigger problem is that the wounds caused
by the worms are an open door to Aeromonas or Pseudomonas infections
because the koi’s resistance is just emerging from the wintertime slowdown.
Tip
You can assume that any koi you buy in late winter or early spring will come with a few anchor worms.
How you get rid of them
You can physically remove the worms by sedating your koi (see the section “Sedating Your Koi, Giving Injections, and Other First-Aid Tasks” at the end of this chapter), placing it on a wet towel on a table near the quarantine tub,
and pulling off the anchor worms with tweezers. This is a very time- and labor-
intensive job.
Fortunately, Dimilin, the trade
name for diflubenzuron, is a proven, safe way to kill anchor worms in a pond.
The dose is one gram per 1,000 gallons. Mix the powder with 1⁄2 cup or so of
pond water and then sprinkle the treated water over the surface of the pond. If
you can’t obtain Dimilin, substitute Program (Lufernon), the anti-flea medication
for dogs. It works the same way and, like Dimilin, is nontoxic.
To use Program, follow these
steps:
1. Pulverize one large-dog-size tablet per 1,000 gallons of water.
2. Add the powder to an empty gallon milk container.
3. Add water, snap on the lid, and shake to mix the two.
4. Shake the mixture as you distribute it around the perimeter of the pond.
5. Turn off your UV sterilizer and remove any carbon you have in your filter while using these medications. At the end of a week, turn on your UV sterilizer and replace the carbon in your filter.
Depending on the temperature of
your water, the treatment takes four to five days to eliminate the anchor worms
or lice. We waited a week, just to make sure the problem was eliminated.
Apiosoma
Apiosoma is a protozoan
parasite that looks like a vase with a fringe of cilia (hairlike
projections) around the mouth of the vase. It’s too small to be easily seen
with the naked eye. Typical symptoms of this parasite include
- Heavy mucous production.
- Clamped fins.
- Respiratory distress.
- Head flicking (to try to dislodge the parasite — to no avail).
- Loss of appetite.
- Big head (the result of little appetite; the thin koi’s head seems too big for its body) — this symptom indicates a heavy Apiosoma infection.
- Add salt to the pond at a concentration of 0.3 percent (three pounds per 100 gallons in your pond).
- Employ a salt bath with a 2 percent salt solution.
- Add a commercial anti-parasite to the pond (malachite green and Formalin).
- Add potassium permanganate at 1.5 grams per 220 gallons (1,000 liters).
Secondary bacterial or fungal
infections are expected, so be sure to read about these in this chapter and be
prepared to treat them as well.
Sometimes a concentrated salt
bath is good for koi with a particularly stubborn affliction. In this case, you
give your koi a salt bath as follows:
1. Make a 2 percent solution (not 0.2, but ten times that!) by using 1 pound of salt to 5 gallons of water and making sure the salt is dissolved.
2. Place the koi in the bath and watch it carefully.
In two to five minutes, the koi loses its balance and falls to one side.
3. When this happens, remove the koi and return it to the hospital tank or the main pond (see the section on hospital tanks later in this chapter).
You can repeat this process after
two days for a total of two baths.
Chilodonella
Chilodonella look a bit
like transparent coffee beans under the microscope, with cilia lining the cleft
underside of the beans. Like other protozoans, these are too small to see with
the naked eye; they are diagnosed with a skin scraping. Irritation from
Chilodonella can cause koi to drag their faces and bodies along the pond bottom
or sides. These protozoans are most aggressive when pond temperatures are lower
than 68 degrees F.
Symptoms of Chilodonella differ
depending on which area of the koi is most heavily infested. For example:
- The koi may become lethargic and hold their fins clamped to their sides.
- The koi may remain near filter outlets because their gills are affected and can’t function well.
- The skin may be covered by a grayish-white film, even covering the eyes.
- The koi have respiratory distress.
- Flashing and scraping are typical.
Treat Chilodonella with one of
the following methods:
- A concentration of 0.3 percent salt
- Potassium permanganate at 1.5 grams per 220 gallons.
Tip
Treat topical damage caused by this parasite with propolis or malachite green.
Costia
Costia, more correctly
known as Ichthyobodo necatrix, is a pear or “comma” shaped protozoan
that moves by means of long, thin appendages known as flagellum (a second pair
is used for feeding). Invisible to the naked eye, Costia’s “jerky”
swimming motions are readily observable under magnification of 200–400X. Costia
attaches to the koi’s skin and gills, and feeds upon the tissue there.
Koi infected by Costia will
cease feeding, become lethargic and gasp for air, and will often excrete excess
mucus.
Costia are best eliminated
by treating the pond with potassium permanganate, which can be purchased at
your pond store or ordered online. See the section on flukes later in this
chapter for specifics concerning the use of this medication. Additional
airstones should be added if the fish appear to have trouble breathing.
Fish lice
Fish lice, or Argulus, are
crustaceans, like anchor worms. They look like small dots of clear jelly, with
dark eyes on one end of their circular body and cilia at the other end. They
pierce the koi’s skin in order to feed and then inject an anticoagulant so they
can feed unimpeded. The anticoagulant has a toxic effect on the koi, and may,
by itself, be powerful enough to kill small koi. See Figure 13-2 for an
illustration.
Figure 13-2: Fish louse,
solo and pestering a koi.
Adult fish lice are large enough
to see with the naked eye, ranging in size from just under 1⁄8 inch to 1⁄3 inch
across. Infected fish or plants from an infected pond can bring the lice to
your pond. Even something as innocent as a wading bird can transmit fish lice. (What
are we saying? In koi-world, innocent and wading birds don’t go
together — all the more reason to discourage visits by any wading birds!)
The presence of fish lice is irritating
for at least two reasons:
- Infected koi swim erratically, flashing and scraping against the side of the pond to dislodge the lice.
Koi can damage their skin in this scraping process, opening an avenue for secondary infection.
- With a heavy infestation of fish lice, the koi cease feeding and become lethargic swimmers.
You can remove fish lice from
anesthetized koi with tweezers and then dab the removal site with propolis.
(See the section “Sedating Your Koi, Giving Injections, and Other First-Aid
Tasks” later in this chapter.) Treating the pond with Dimilin and Program,
however, is easier than removing the fish lice manually. Use the same dose as you’d
use for anchor worms (see the earlier section “Anchor worms” for specifics on these
treatments).
Flukes
Body and gill flukes feed on the
mucous on a koi’s body and literally hook themselves into place. Although
they’re very common on koi, they usually don’t cause a problem unless the koi
is weakened by another disease. Treat the flukes with potassium permanganate.
To treat a pond with potassium
permanganate, follow these steps:
1. Turn off the pond filter and dissolve one teaspoon per 1,000 gallons in a bucket of water.
2. Add the pink solution to your koi pond. (The water will turn pink, and that’s good.)
3. If the pink coloration disappears within 45 minutes, add another 1⁄2 teaspoon per 1,000 gallons. If the color disappears after two hours, re-dose with 1⁄2 teaspoon per 1,000 gallons.
4. At the end of ten hours, change one-third of the pond water and turn the filter on. Repeat in seven days.
If the infestation is severe and
the flukes are on several fish, you may want to use Fluke Tabs, a
medication available at most pet stores, that is specifically designed to fight
this parasite. Check the instructions on the box, but generally you can use one
tablet per 100 gallons of water.
Ich
Ich (also spelled ick)
or white spot looks like little white spots on the koi’s skin and
generally appears when koi experience a sudden temperature drop. The
infestation can only be controlled by killing the organism in its free-swimming
stage, so be sure to follow the medication timetable carefully.
Symptoms of ich infestation are
- Koi may stop feeding and begin rubbing their bodies against the pond sides and bottom.
- They may produce so much mucous as a defense against ich that they take on a whitish tone.
- They may experience respiratory distress when ich attacks the thin, oxygen-absorbing skin that covers the gills.
Tip
Ich is very contagious and has two life stages: a nonswimming stage on your koi, and a free-swimming stage. The only time ich is vulnerable — and therefore treatable — is the free-swimming stage.
The commercial anti-ich
treatments are very effective. Several products are available, but be sure to
follow the instructions provided by the medication.
Bacterial Infections: Bad News Anywhere
Bacteria attack a fish when the
opportunity presents itself. Often this will occur secondarily to another
disease or injury, or when the fish’s immune systems are weakened by the stress
of shipment, handling, poor water quality, or water temperatures that are too warm
or too cold.
The exterior attack
When the
bacteria sets in on the outside of a koi, the koi develop open wounds or ulcers
that spontaneously appear
- On the mouth
- On the belly
- As holes in the fins
- As red streaks on the fins
Ulcers
The most common cause of external
ulcers are two bacteria, Aeromonas and Psuedomonas. Although
these bacteria are almost always present, they move in when your koi become
stressed (particularly in the spring when water temperatures are around 60 degrees).
Other typical symptoms are excessive mucous production and red areas around the
edge of the ulcer.
Tip
Take the following steps to treat ulcers:
1. Net and bowl the fish.
2. Clean the wound with hydrogen peroxide or mercurochrome.
3. Spray a multipurpose antibiotic like Polysporin on the wound.
4. Repeat Steps 1 through 3 two more times at three-day intervals.
If you can move your koi to a
heated hospital tank for this period, so much the better.
When more than one or two fish
are affected, do one of the following:
- Treat by feeding an antibiotic-laced diet for two weeks. (Obtain the diet from your koi dealer or an online koi-product vendor.)
- Add potassium permanganate to the pond at the rate of 1.5 grams for 220 gallons (please see the “Flukes” section earlier in this chapter for details concerning treating koi with this medication).
Fin rot
During the warmer summer months,
koi may seem healthy yet display signs of fin rot (also called gill
rot, mouth rot, and skin columnaris, depending on where the rot
attacks). Fin rot is actually caused by the combination of warm pond water and
high ammonia and pH levels. (Can you imagine being in water so toxic that the skin
on your appendages rots? Oh, ouch!)
These are the affected areas and
their symptoms:
- The fins: The first signs are reddening of the fins, then white patches at the tips of fins where the circulation has been destroyed, then erosion of the fins.
- The gills: The gills become mucous-laden and then spotted with white; eventually necrosis develops.
- Mouth rot: This disease appears as a small, white spot near the nose that soon reddens and spreads.
- Skin columnaris: The first signs are small, white patches, then heavy mucous production; red patches appear on the skin and some scale sloughing may occur.
Koi with columnaris feed poorly,
especially if the mouth is involved. They stay near the filter outlets or under
the waterfalls, where the water has more oxygen.
Lower the ammonia level by doing
one or more of the following:
- Partially change the water on a daily basis.
- Cool the pond to approximately 75 degrees F.
- Add an ammonia remover such as Zeolite or AmQuel Plus.
- Evaluate and upgrade the processing capacity of your biofilter, making sure it is large enough for your pond’s water volume and the number and size of the fish in it.
When the problem’s been solved,
the fin rot stops and the fins can heal. Treatment for your koi consists of
dabbing the sores with malachite green, followed by feeding propolis and an
antibiotic feed such as MediKoi for at least ten days.
The inside attack: Internal infections
Internal bacterial infections are
always serious, and the outcome is not guaranteed. The disease is called bloater,
pine cone, or dropsy. In these cases the following occurs:
- The fish swells with the inflammation (sometimes more so on one side than the other).
- The pressure pushes the scales away from the body.
- The pressure on the fish’s air bladder makes the fish swim awkwardly.
- The fish’s eyes protrude.
See Figure 13-3 for an example of
this disease.
Treatment for dropsy usually
includes a stay in a hospital tank, if possible. Add salt for a 0.3 percent
level and slowly heat up the tank or pond to 77 to 85 degrees. In addition,
some koi owners offer one of the following:
- An antibiotic diet that’s safe to use with salt
- A probiotic feed (feed that has friendly bacteria added)
- Very small amounts of plain yogurt that they hand feed via a syringe inserted into the mouth and down into the alimentary cavity, or what passes for a stomach in koi.
Preventing bacterial infection
Tip
You can forestall ulcers and dropsy by closely watching your pond’s water quality and temperature and by adding a probiotic to the water. Probiotics are friendly bacteria. When you add a probiotic (KoiZyme is one) to your pond, you install friendly bacteria that will compete with Aeromonas or Pseudomonas for any available nutrients in the water (as in koi waste). The bad bacteria die. The good bacteria live.
Figure 13-3: A koi with
dropsy (also called pine cone or bloater) disease.
Remember
Combine a probiotic with a good filtration system, and you stop a lot of health problems in their tracks.
Swimmer’s Gill (Or Skin): Fungal Infections
Fungus can attack any weakened portion of a koi, from the skin to the gills. It usually takes hold opportunistically, when the koi are stressed by injury, disease, shipping, poor water quality, or inappropriate water temperatures. Be sure that you always check for the presence of fungus when your fish suffer an unrelated trauma or illness.
Got fungus on the gills?
Gill fungus attacks the gills (go
figure), and unless you’re paying close attention, one day your koi’s doing
fine and the next day he’s hanging around the waterfall. A short time later,
he’s belly up.
Remember
Gill fungus usually crops up in the spring either in ponds that don’t have adequate aeration or in ponds whose fish-load has outgrown the filtration system. The koi act lethargic, feed poorly — if at all, and stay close to the surface of the pond. When you net and bowl one, the gills look like they have gray cotton growing on them.
Salt, in one percentage or
another, is a classic koi treatment, or you can use one of the commercial fungus
treatments.
Fluffy white fur isn’t always a good thing
Cotton wool or cotton
ball disease is a charming name for a nasty condition. It’s caused by Saprolegnia,
a fungus that grows when bad water quality stresses the koi. Expect to find
it when the water contains quantities of uneaten food and when the pond has too
many koi for its size.
The koi develop what looks like a
fine-textured fur coat over their bodies that’s actually mold growing on their
skin. Sometimes the fungus looks like a pale-orange or ivory-colored layer,
much like the mold that grows on items left too long in the fridge See Figure 13-4
for an illustration of what koi fungus looks like). As the disease progresses,
the fungus grows longer, cottonlike tufts.
Treat this disease by correcting
the conditions that lead to the outbreak:
- Decrease the number of koi in the pond. (Show ponds work well as holding stations for the excess.)
- Improve water quality via partial water changes, an upgraded filtration system, an ammonia remover like AmQuel Plus or Zeolite, and increased aeration.
Tip
You can also use medication against the fungus. Adding methylene blue (a dye commonly used as a fish medication and available at most pet stores) to the pond at a rate of 1 teaspoon per 700 gallons helps kill the fungus, but individually treating each affected koi in a quarantine tub stops the progression of the disease much faster.
Figure 13-4: Koi with a
white fungus patch on its back.
Either sedate the koi or hold it
so you can remove the patches of fungus with a cotton swab. Then dab the
affected spots first with malachite green and then with propolis. (See the
section “Sedating Your Koi, Giving Injections, and Other First-Aid Tasks” later
in this chapter.) Return the fish to the quarantine tub and watch closely to
make certain no secondary fungal or bacterial infection sets in.
The Three Greatest Viral Threats: Pox, SVK, and KHV
Diseases caused by a virus are
tricky. Only a few vaccines have been developed to fight them, and those or koi
are in the very early stages. With a koi virus, you and your koi pretty much
have to take chances.
In addition to carp pox (koi’s equivalent to the dreaded chicken pox), you need to know about two other viruses because they’re far more life-threatening: spring viremia of koi (SVK) and koi herpes virus (KHV).
Forget the chicken — koi get carp pox
Carp pox appears as tiny, raised
drops of paraffin on your koi’s body or fins. The colors may be white, pink, or
gray, and you can flick them off with your fingernail. Koi show no behavioral
changes to indicate illness, but infected fish are carriers. The pox is a self
- limiting disease, meaning it doesn’t kill adult fish; however, it has a high
mortality rate on koi younger than two months. There is no treatment, but
research is underway for a carp pox vaccine. Adult fish in otherwise good
health will survive, but you should isolate them from young koi and any new
fish that you may acquire. You may, therefore need to set up a new pond, give
infected fish to someone who maintains others with the disease, or resign
yourself to not breeding or acquiring new fish.
Carp pox is most prevalent in
early spring, when water temperatures are less than 68 degrees. If your pond
suffers an outbreak, move the fish, drain the pond, and disinfect with 200
parts per million chlorine for one hour to sterilize surfaces; use a quaternary
ammonium compound like Roccal at 500 ppm on nets.
Spring viremia of carp: Predator
of koi at their most vulnerable SVC
is a virus that attacks koi, other species of carp, and goldfish. It becomes
active in water temperatures of 40 to 68 degrees, when koi have essentially no
immune system.
Symptoms include lethargy,
awkward swimming, skin ulcers, and areas of hemorrhage adjacent to the ulcers.
The body may bulge with septicemia (blood poisoning); bloody mucous may
seep out from the vent. SVC is highly contagious and has a high mortality rate,
especially for young koi.
Remember
There is no treatment for SVC, and surviving koi may become carriers of the virus. It is also a reportable disease. In other words, if it’s been diagnosed by a USDA-approved laboratory by using a polymerase chain reaction (PCR) test (which is the only definitive diagnosis), federal officials must be notified. The feds will come to your home and require you to depopulate your fish and disinfect your pond.
Tip
If you decide against an official diagnosis, sterilize your pond by draining it and washing it down with a 500 parts per million chlorine solution. Allow the bleach solution to stay on the pond walls and floor for ten minutes before rinsing.
The quick, sneaky killer: Koi herpes virus
KHV is a DNA-based herpes virus that
affects only the common carp and koi. The virus becomes active when water
temperatures are between 64 and 81 degrees and it spreads via direct contact, exposure
to fecal material, or infected water.
Warning!
Koi with KHV become lethargic in their swimming, stay near the surface, and have difficulty breathing. Their gills become mottled red and white, indicating some hemorrhaging and blood clotting dysfunction. Death usually follows 24 to 48 hours after the symptoms appear. The diagnosis is confirmed with a PCR test, but the disease is not notifiable (in other words, federal veterinary officials need not be alerted).
Post mortem examination shows
infections by bacteria and fungus on all skin surfaces, including the gill
surfaces, so obviously KHV plays hob with a koi’s immune system.
Remember
There is no treatment for KHV. You can prevent its spread by using a quarantine tub and by paying close attention to sanitation. For a pond where KHV has been confirmed, follow these steps:
1. Empty and scrub the pond with a sanitizer such as
- A solution of 200 parts per million chlorine
- A mixture of 0.26 ounces of Roccal Plus D to a gallon of water
2. Rinse all surfaces.
3. Sanitize all pond equipment, nets, and bowls.
Technical Stuff
KHV has been reported from the U.S., Europe, Israel, and Japan. The 2005 outbreak in Niigata was traced back to a single, borrowed, imported koi. The unfortunate result was the depopulation of at least five koi breeders’ stock.
At koi shows, officials may decide to limit possible exposure to KHV by keeping all the fish belonging to one individual in his or her own show pond or ponds. Judges go from pond to pond, netting and bowling all the koi pertaining to the class being judged at that time. This is called the English
style, as opposed to the Japanese syle of grouping all koi of a particular
show class in a single show pond. Nets and bowls are currently restricted to
one-container and one-koi use, and they’re sanitized with Roccal between uses.
Roccal can be diluted to 0.5 ounce per gallon and used to disinfect hands
between handling koi.
Keeping your old koi safe from viral infection
Your best bet for avoiding KHV is
to select your koi vendors carefully and use your quarantine tub for all
additions to your pond.
You can select quarantine
conditions that predispose new koi to developing SVC or KHV if either virus is
already present. The advantage in this safety net is that only your new koi
die, not your entire collection. Essentially, you simply change the temperature
of the quarantine tub and wait for signs of SVC or KHV to show up.
Follow these steps:
1. Place your new koi in the tub but don’t turn on the heater. Keep temperatures of the tub in the low 60s for two to three weeks.
2. Turn on the heater, increasing the temperature no more than 5 degrees within a 24-hour period until the water is 75 degrees.
3. Keep the tank at that temperature for two to three weeks.
If SVC is present, it will
manifest itself when the water temperature’s between 40 and 68 degrees; KHV
will manifest itself when the water’s between 72 and 81 degrees. Unfortunately,
the infected fish will die. Be sure to disinfect your quarantine tub as
described earlier before using it again.
Setting up the Hospital Tank
Tip
The hospital tank is much like the quarantine tub — an isolation tank where you can treat only the fish that need it. Always have at least two koi in a hospital tank, even if only one of them needs the treatment. Koi are not solitary creatures and the stress inherent to sickness and treatment will be lessened if they have company. A lower stress level will benefit the immune system and aid the fish in its recovery.
You can create a hospital tank
out of a stock tank, a show tank, or a 150-gallon or larger polyethylene bin. A
bottom drain fitting allows you to clean and drain it more easily, and they’re
usually salted to 0.3 percent.
Set the hospital tank up in a
spot that’s out of the sun and protected from adverse weather. Use the
following equipment:
- A filter: Either a standard three-compartment filter or a polybead filter (see Chapter Making Sure Koi Are Right for Youfor more on these filter types).
Set the filter up to pull from the bottom drain or a retrofitted bottom drain; another variation is to place the inflow and outflow pipes over opposite ends of the tank.
Add a foam prefilter to the filter intake to protect your fish from being grabbed by the filter suction.
- A heater: 200- to 300-watt heaters are large enough for a 100-gallon tank.
- A thermometer: One used for an aquarium will work just fine, but pond thermometers are larger and easier to read.
- An aeration pump with an airstone: This equipment ensures adequate aeration and water circulation.
Drape the airstone tubing over the edge of the bin and place it as near to the bottom of the bin as possible; the longer distance the bubbles travel, the greater the oxygen absorption.
Remember
Do not turn on the heater until you put your koi into the tank, and only increase the temperature 3 to 5 degrees a day — any faster is too fast for your koi to adjust to. Because the immune system of a koi is most efficient when the fish is warmed, keep the water between 78 and 82 degrees.
Cover the hospital tank with bird
netting or with a fitted mesh cover. Distressed koi and koi placed in
much-smaller-than-usual housing tend to jump.
Sedating Your Koi, Giving Injections, and Other First-Aid Tasks
In any case, you’ll need to
anesthetize your koi. You can do this safely and easily, but the process
requires your undivided attention. Follow these steps:
1. Gather the equipment:
- A koi bowl or child’s wading pool with a few gallons of pond water aerated by an airstone
- A nearby table covered with wet towels and a few more wet towels to prop up the koi
- The anesthetic (three choices), added to the koi bowl or pond:
Tricaine-S added to the water in the bowl at the rate of 200 milligrams per 2 pounds of koi
Four drops of Oil of Cloves per gallon of water in the bowl
Six drops of Eugenol added to the water in the bowl
- A tuberculin syringe (you can usually get these at your local pharmacy in the section with diabetic supplies)
- A broad-spectrum antibiotic: Baytril or Amikacin
2. Add the koi and watch him until he rolls over.
This only takes a few minutes. The duration of the anesthetic effect averages 4 to 10 minutes, but is affected by a host of factors, and is therefore highly variable. It is best to review everything beforehand, so that you will be able to work swiftly and effectively. If the fish begins to recover before you are finished, do your best to complete the task at hand. Try to avoid a second period of anesthesia, but if you must do so, wait for 1 hour before putting the fish “back under.”
3. Lift the anesthetized koi to your table and prop him up with the towels.
4. There are two sites for injecting your koi. Pull the pectoral fin towards the fish’s mouth, and inject the antibiotic into the fleshy lump behind the fin. The older method is to inject into the koi’s belly, between the pelvic fins (see Figure 13-5).
Figure 13-5: How to give a
koi an injection.
To treat an ulcer:
1. Prop the koi so the ulcer is uppermost.
2. Use cotton swabs to first dry the wound and then paint the ulcer with malachite green, changing the swabs as needed.
3. Add spray-on propolis (for its antioxidant qualities) over the malachite green.
To remove a specimen:
1. Take a pair of very sharp scissors to clip off the very edge of a fin or use a moistened swab to tease up a bit of the mucous and debris at the edge of a wound.
2. Place the specimen or swab in a specimen tube for mailing to a lab, and seal the tube. (See the earlier section “Examining your sickly fish” for more about this process.)
When the operation is over:
1. Place the koi in a blue bowl filled with fresh water from the pond. (The water should be heavily aerated.)
2. Keep the koi in the bowl until normal breathing is reestablished. (Move him back and forth to put fresh water over the gills until he begins to move his fins or twitch his gills.)
3. Wait another minute and then put him back in the pond; watch him for a few moments to make certain he’s capable of swimming under his own power.by R.D.Bartlett and Patricia Bartlett
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