Infectious Diseases of Goldfish and Koi
- by Doc Johnson
**Please note: Blue text is notes inserted by
Earthworks Ponds & Watergardens for our readers clarifications and was not
originally part of Doc Johnson's article.
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| If I had to guess, I would guess that every singe hobbyist
in the whole world WILL encounter Ich at some time. Usually the meeting
occurs early on, as a beginner, before water quality parameters such as
Ammonia, Nitrites and 'The Cycle' become more familiar, and 'Quarantine' is
just a high ideal observed by a few pathetic perfectionists. |
- What is 'Ich'?
- Freshwater Ich (Ichthyophthirius multifilis) is a ciliated protozoan
that encysts under the epidermis of the fish; and, in its encysted
condition, causes small white spots all over the fishes body and fins.
In some cases, Ich spots may be present, but will not be visible. You
may still see them under the scope, or you may see them exclusively on
the gills. This is how infected fish may get into a tank without being
detected, even if quarantined for a period of time. Asymptomatic
carriers can sustain a population of Ich in a tank or pond for an
indefinite period. Sometimes an owner will purchase a new fish who,
being immunologically naive to Ich, will contract the condition
immediately upon introduction to an 'endemic' (already infected but
asymptomatic) group of fish. If a fish contracts Ich, and survives
without treatment, they have shown strong immunity to re-infection,
indicating that the potential for a vaccine exists, and is being worked
on at University of Georgia and other institutions. It would have
astonishing impac on the Catfish industry if it could be achieved.
Ich rapidly kills smaller tropicals and goldfish, while often sparing
the larger varieties (fish such as Oscars and Koi). Damage to the gills
is the primary way it kills, but damage to the skin with secondary
bacterial infection may also figure prominently.
Its life cycle is roughly 2-5 days, but can be longer (5+ weeks!) if the
water is cool, much shorter if the water is warmer. There is the old
rumor that warm water eradicates it. This is substantially true when
temperatures exceed 85 degrees, however; there are strains coming out of
Florida and detailed by researchers at University of Florida that can
survive and thrive up to NINETY degrees or more! Recall that many of our
bread and butter species of tropicals come from Florida, and so may
harbor this heat tolerant strain.
The parasite has a phase that encysts in the epidermis of the fish as
previously stated (called a theront). It matures under the skin and
finally drops off, falling to the bottom (becoming a trophont) to divide
into numerous (hundreds) of tiny swarmers (tomites) that actively seek
out a host on which to encyst and renew the cycle of infection. Because
an important phase of its life cycle occurs on the bottom of the
aquarium, it is for this reason that you can help limit infections with
water changes made by siphoning the gravel, removing those dividing Ich
packets.
Interestingly, some research at Oklahoma has revealed a strain of Ich
that does not have to leave the fish and whose Ich packet (trophozoite)
remains under the epidermis (safe from medications) and the tomites
swarm out under the epidermis. The lesions look much like Carp Pox
lesions, being large, flattened, and waxy looking. This parasite is
harder to clear because it is the free swimming tomite that we can kill
with medicaments.
Prevention is attended at the wholesale level by the maintenance of a
0.3% salt solution which crenates (kills) the emerging tomites. We do
not recommend that you as a hobbyist maintain this salt level all the
time because live plants can be killed by this, and all species of fish
are NOT universally tolerant of this. Still, many have found that salt
is a very effective annihilator of Ich infections if normal precautions
are observed.
- There are numerous reasons to reach
for salt, first, for Ich.
- 1) It does not harm the majority of fish species.
2) It does not push sick fish 'over the edge.'
3) It eliminates, QUICKLY, most of the serious pathogens of tropicals.
4) It does not get bound out of the system by organics or sunlight.
5) It does not pose a health risk to humans contacting it.
6) It is CHEAP, CHEAP, CHEAP.
7) It WON'T harm your filter if administered in divided doses.
Salt can be used in freshwater systems by adding one teaspoon of salt to
each gallon of water every twelve hours for three treatments. You are
gradually increasing the salinity to a level of 0.3% or three teaspoons
per gallon total. The dose goes in gradually over 36 hours to avoid
shocking the filter (especially Nitrobacter, which results in a short
Nitrite surge). Some sensitive fishes will also do better when salted if
it's added so gradually. Salt should be of the non-iodized table salt
variety, or an Aquarium salt recommended by the Pet Shop. Live plants
can be killed or yellowed by this, so be careful to remove these before
treatment. As a general rule, plants with a defined root system will
usually survive salting, while floating varieties like Anachris, Cabomba
and Wisteria are flatly killed. My Apons died back 50%, Cryptocoryne
couldn't care less, Pennywort hated it but did not die, Anubias yellowed
and recovered, in the ponds, Lilies yellow marginally but do not even
stop flowering. Iris is impervious, and Hyacinths hate it but they only
yellow in the older leaves, and bounce right back.
Most pond plants in a well designed system will
tolerate the recommended salt levels for the treatment period of 5 to 7
days time. It is necessary to do a partial water change out to
lower the salt concentration in the pond after treatment. This
water dilution will enable the plants to avoid excessive stress and
shock and maintain a healthy state.
Is there a way to measure the salt once added?
Koi Medic has a digital salt meter that can be
very useful for working with salt levels in the pond.
- What can salt do for me?
- Salt at 0.3% is credited with the clearance of the following:
Ichthyophthirius (72 hours at tropical temperatures)
Chilodinella (24-36 hours)
Costiasis (Ichthyobodo necatrix)
Almost every single Trichodiniid/Tripartiella organism.
Glossatella (24 hours irregardless of temp)
Scyphidia (24 hours irregardless of temp)
Epistylis (24 hours irregardless of temp)
Trichophrya (24 hours irregardless of temp)
External Tetrahymena
Inhibits trematode reproduction, clears 30% of adults.
Inhibits Lerneiid reproduction
- Is there a type of fish to be careful
with?
- Salt has been reported in some instances to cause health problems
for the following fish:
1. Wild caught Discus. (Captive born specimens have no problem at all.)
2. Some Brokis britskii catfish
3. Otocinclus
4. Rafael Catfish
5. Ram Cichlids
6. Neon tetras
7. Cardinal Tetras
8. Tiger Barbs and Sharks die suddenly if chased with a net while
salted.
Note. The divided dosing schedule has alleviated alot of these problems,
but use salt at your own risk in these cases. Sometimes the numbers of
fish you have from these groups make them somewhat 'expendable' in the
interest of saving the other fish.
- How long do I leave it in the water?
- Fourteen to 21 days may be required to totally eradicate certain
parasites at certain temperatures. Rest assured, it could stay in the
water forever. But for Ich it could also be
removed within seven days and recurrence of Ich would be unlikely
if temperatures during treatment were around eighty degrees F. Ten to
fourteen days is suggested 'for best results' with Ich.
Removal is by simple partial water changes. Be careful that the effluent
water is not wasted onto a precious Japanese Maple or your Dad's best
Bermuda grass as it could do it some damage.
I traditionally use salt for most protozoan parasites, especially Ich,
and the wholesalers/retailers who rely upon it have thanked me for the
tip. To name just a few, Suburban Water Gardens, Blue Ridge Hatchery,
One of Kind Koi, Willow Pond, Finn's Aquatics and Marine Life all
provide superior fish to their retailers through the use of 0.3% salt in
all freshwater species but their most sensitive South American imports.
I use salt because so many other medications for Ich are caustic to the
fish, reduce dissolved Oxygen levels, and can tend to disable the filter
bacteria that remove Ammonia.
- To recap my points, here's the nuts
and bolts of Salting Ich..
- 1. Remove valued live plants.
2. Raise temperature to 80 degrees, tops.
3. Increase aeration!
4. Add one teaspoon of salt per gallon.
5. Twelve hours later, add another one teaspoon of salt per gallon.
6. Twelve hours later, add another one teaspoon of salt per gallon.
7. Within 48-60 hours of the second salt dose at 80 degrees, the Ich
will be gone.
8. Leave salt in the water for another 3-5 days unless you're worried
about your live plants.
9. Remove salt via partial waterchanges. (30-40% at a time if desired).
- Flukes
- Freshwater flukes occur in all parts of the world on numerous
species of fishes. By their name, you might expect them to be visible to
the naked eye, however, they are microscopic.
Flukes occur in two major classes, that is; Dactylogyrus, the famed Gill
Fluke, and the second class is Gyrodactylus, the Skin fluke. There are
certain morphological differencesbetween these two classes. Under the
microscope, you would notice that the Dactylogyrus fluke has several
pairs of eye-spots, and they also lay eggs. In a specimen of
Gyrodactylus, you would only see an embryo inside, with no eyespots in
the adult.
The class Dactylogyrus occurs in over a hundred different species.
Notable members of the dactylogyrus group are the common and extremely
damaging D. vastator and the amazing D. extensus (the common Israeli
Fluke) which can function very efficiently in very cold water.
On average, Dactylogyrus lays about 2 eggs per hour in cold water (12o
C), and as many as 20 eggs per hour in warm water (24o C).The eggs are
swept out from under the gill cover into the environment. It takes the
eggs almost a month to hatch in the wintertime, but only 4 days to hatch
in the peak of summer. 4 days after hatching, the tiny larva becomes
free swimming and can infect a new host. Ten days after attaching to a
new host, the new larva matures and can begin egglaying activity. The
adult will live anywhere from two weeks to a month and then perish.
However, in cold water, individual adults and eggs can survive in
hibernation for five to seven months. Most of the research supports the
following mathematics, and that is: In the summer, one adult
Dactylogyrus fluke can produce 2,320 individuals in only thirty days.
Gyrodactylus flukes reproduce by producing live young which set about
parasitizing the host immediately. After the first fertilized egg moves
into the uterus to be gestated, delivery occurs five days later and more
eggs move into the empty uterus to resume the cycle. A female
Gyrodactylus is always gestating, and they are so prolific that the
embryo inside the mother actually gestates a fertilized egg from its
mother in its uterus! One adult Gyrodactylus can produce 2,452
individuals within 30 days during the summer. As with Dactylogyrus, the
adult will live anywhere from two weeks to a month and then perish.
However, in cold water, individual adults and eggs can survive in
hibernation for five to seven months.
Most flukes agree that the best place to live is on the surface of a
fishes' skin or gills, feeding on blood, and mucus found there. In my
studies of these parasites, I have found considerable overlap of the
different species on a single fish. Dactylogyrus seems to have no qualms
about showing up in a skin scraping, and Gyrodactylus seems to have
equal affinity for the gills.
All types of flukes share the same microscopic features: On their front
(anterior) end we see suction cups, and on their foot end they are
equipped with an array of sharp haptens or hooks. They can attach with
either structure, but most often we see them deeply hooked into the skin
or gill, exploring the surface of the fish with the suctorian end.
Flukes are easy to diagnose microscopically. A skin scraping should be
taken with a plastic cover slip from under the chin, between the gill
covers. Another sample should be collected from the side of the body;
scraping from there and out onto the tail and off the tip. The mucus is
placed with a drop of pond water on a slide an viewed at 40x total
magnification with the iris diaphragm closed down, and lighting low
enough for comfort. You should see 'wormy' looking organisms. Usually
they are extremely active. They are capable of elongating and
contracting with both amazing speed and dramatic agility. Especially in
water containing 0.3% salinity, usually flukes are all you could hope to
see because the other types of parasites (ciliated protozoans) are
annihilated by that salt level.
Their primary mode of killing would ostensibly be through the
accumulation of large numbers. Especially in fish fry, the numbers of
flukes encountered are accepted as the cause of mortality simply because
they take such a toll on the victim when they occur in large numbers.
Based on observations made in practice, however, I would like to
introduce my opinion of how just a few flukes can kill a larger fish.
In the process of attacking a host, the flukes dig deeply into the
epidermis and gill tissue with their haptens. Regardless of species, the
flukes are known to carry and inoculate pathogenic bacteria. Flukes from
certain areas, and on certain batches of fish carry more and more
dangerous and virulent bacteria on their haptens. In this way, discovery
of a few flukes on the gills or skin can account for rapid and mortal
outbreaks of Aeromonas and Pseudomonas funrunculosis (Ulcer Disease).
Control of flukes has become increasingly easy with contemporary
medicine. Potassium permanganate has been shown to be effective when
applied as an eight hour bath at one gram per hundred gallons (2 ppm) or
when dosed daily at 2 ppm for five days consecutively. Alternatively,
some have found that despite it's negative effects on fish and filter,
that Formalin is effective in eradication of fluke adults, with a second
treatment (three days later) serving as clean-up for the emerging young.
Finally, Fluke Tabs® (Aquarium Products, Glen Burnie MD) have also shown
strong effect in warmer water at one tablet per ten gallons applied in
two treatments 4 days apart.
- Anchor Worm & Lice
- Argulus is a crustacean or branchiurian aprasite most commonly
encountered in ponds, but they are also found in aquaria. They are
easily detected when they strike. They are greenish disc shaped
organisms with suckers and small legs. They even have a pair of eye
spots on the anterior end. They spend their time darting around in the
water away from, and also directly on the fish. They lay their eggs in
tubular structures on the glass and ornaments.
They can be very destructive to fish stocks.
They carry Aeromonas and other bacteria on their feeding stilletto and
thus infect each fish they bite.
Treatment is by the application of the insect growth regulator, Dimilin,
or Diflubenzuron. Anchors Away is perhaps the only fish-labelled form of
Diflubenzuron which is commercially available.
Another treatment is more dangerous: Organophosphates like Trichlorfon,
masoten, Dylox, Dipterex, FLAW, Malathion and Fenthion. I resist the use
of these, because losses may result. Dimilin (the active in Anchors
Away) is superior to these compounds when fighting Argulus.
Lernea elegans, the most common type of Anchor worm affecting Koi, is a
real threat. They attach ventrally, they hold on for about 14 days, and
they reproduce copiously. The wounds they create almost always infect
with Ulcer disease bacteria, Aeromonas, and then you have two problems.
Treatment can be undertaken with Malathion, Fenthion, Trichlorfon, Dylox,
Dimilin, and SALT. Salt works by killing the freeswimming reproductive
forms. Malathion just kills the Lernea dead, but is dangerous to the
fish. Fenthion is slow but safer. Dimilin is great if you can get it.
Anchors Away is perhaps the only fish-labelled form of Diflubenzuron
which is commercially available.. I do recommend removing any adults you
see attached and swabbing the wounds with Iodine or mercurachrome. I do
recommend also feeding an antibiotic food when you see Lernea to head
off problems. Please see the formulary for doses on the various
treatments.
Dimilin:
By weight is 25% Dimilin, 75% inert ingredients.
Active ingredient: Diflubenzuron
Dimilin is a restricted use pesticide with a specific spectrum against
insects and crustaceans.
Therefore, it is highly effective against Lernea and Argulus.Common
names for these parasites are 'Anchor Worm' and 'Fish Lice'
respectively.
Dimilin is toxic to invertebrates*, so don't let the water run into
rivers or creeks.
*(Will kill crayfish, water fleas, etc.)
Mix Dimilin with water and apply at a rate of one gram per 1,000 gallons
to be treated.Published dosage is between 0.03 and 0.06 ppm.
Restated: For 1,000 gallons, mix 1 gram dry Dimilin in some water, mix
well, then sprinkle it over the surface of your 1,000 gallon system.
For 100 gallons, dissolve 1 gram in 100 cc water, then use 10 cc of the
suspension. Do not try to save the rest of the suspension.
If you do not have a gram scale or a balance-beam: 1 gram Dimilin fits
neatly into a level 1/2 teaspoon measure.
1 level (non-packed) teaspoon equals @ 2 grams.As a side note: 1 gram
Dimilin per 150 gallons (tried experimentally) to adjudge the relative
toxicity of the compound was found to cause no ill health in the Koi
tested. (24specimens under 6 inches in length)
Reapply at 30-60 day intervals for season-long control.
Use of this product is illegal. You mus be a licensed pesticide
applicator to use this product. FDA considers this a high enforcement
priority. If you possess or use Dimilin, I would recommend doing so VERY
discretely.
- Bacterial Infections:
- Fish with reddish lesions in the body or fins, fish with swollen
eyes, red mouths or bellies, or those that just die for no apparent
reason may all be affected by bacterial sepsis.
Sepsis is one of the hardest conditions to treat because not only are
the bacteria protected by the fishes tissues and bloodstream, the
internal organs of the fish are often so compromised that even if you
COULD eradicate the bacterial invader, you would lose the fish to other
complications.
If you must try, please heed my advice NOT to add antibiotics to the
water.
There are four concepts to understand concerning fin rot.
First, finrot is usually a bacterial infection which results from any
one of four causes,
1. Fin nipping
2. Parasites like Flukes or Ich inoculating pathogenic bacteria into the
skin
3. Deteriorating water quality, inadequate filtration, or high bacterial
counts in the water because a hobbyist is not using an undergravel plate
and the gravel bed has become stagnant.
4. Poor nutrition
Second concept:
To recover fish, water quality must be corrected even if you start using
antibiotics to kill the primary bacterial invader. Remember that most
any treatment you might use for pathogenic bacteria will likely also
affect your nitrifying (filterbed) bacteria and this can, in loaded
systems that are already barely keeping up, cause Ammonia or Nitrite
accumulations.
Third Concept:
Treat in a hospital tank. A ten gallon with a hood, a heater at about 78
degrees, and a sponge filter all cycled and ready. Treat with
Trimethoprim Sulfa 960mg in ten gallons of water made fresh daily for 6
hours a day for three days. Alternative drugs would be any of the Furan
antibiotics or even possibly, as a very last resort, Maracyn from Mardel
"Labs".
Fourth Concept:
Nutrition is best supplemented with live or fresh frozen foods fed from
a basket feeder. It makes a difference because from a basket feeder,
there is little waste, and fewer food morsels are lost in the tank,
therefore water quality does not deteriorate, bacterial numbers do not
rise, and fish are capable of recovery. Good choices are Ocean
Nutritions Brine Shrimp Plus, or plain brine shrimp, blood worms or
maybe Prime Reef.
So, for finrot, consider an overhaul of the system to optimize water
quality. Consider removing affected specimens to a hospital tank and
treating there. Consider a basket feeder and varying the diet.
One last consideration: Veiltail fishes, like fancy goldfish and
Angelfish, as well as Bettas, are particularly sensitive to high water
borne bacterial counts. Their fins are very large, and vascular supply
to the tips is low, and so bacteria have an easy time feasting there if
the water is very rich in organics and lots of bacteria are being
supported. Veiltails need allot of filtration, and sparkling water.
Sometimes your nose is the best judge, because even if you cannot see
organically rich water with a high bacterial load, you sure can smell
it.
- Salt:
- Salt: Remove submerged plants. Perform a fifty percent water change,
and clean the pond as well as reasonably possible without causing undue
delay in treatment. Apply one teaspoon of non iodized table salt per
gallon of water every 12 hours for three treatments (3 tsp per gallon).
Alternatively, for larger systems, dose one pound per hundred gallons of
water every 12 hours for three treatments (3 pounds per hundred
gallons). Add all at once in the case of epidemic mortality.
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