Up
Potassium
Salt the Wonder Drug
Oxygen
Program
Formalin
Parasites
Medicaction Doses
Nitrite Spike
KHV? NOT

Please read our Quarantine page for the best way to protect you and your fish.

Our Must Have.. page has things you need to SHOW your koi. You will find that these same items are useful for taking care or your fish. Nets, bags bowls, as well as oxygen bottles are items that are Must have. I have also added a complete quarantine system you can order.

 

Koi Herpesvirus Update 2004
Thomas B. Waltzek M.S. and Ronald P. Hedrick Ph.D.

The following article appears in the July-August 2004 issue of California Veterinarian.

In 1997, an infectious disease resulting in massive mortalities of koi (Cyprinus carpio koi), a colorful strain of the common carp (Cyprinus carpio carpio), was reported in Germany (1). In the following years losses continued in Germany and new outbreaks in koi and common carp occurred throughout Europe (Great Britain, France, Belgium, Netherlands, Luxemburg, Denmark, Switzerland, Austria, Poland), Asia (Indonesia, China, Taiwan, Japan), Israel, U.S.A., and South Africa (1-6). The agent responsible for these epidemics, koi herpesvirus (KHV), was first isolated by our laboratory in 1998 from koi experiencing heavy mortality in both the U.S.A. and Israel (3) and has been repeatedly isolated since (6-8). The rapid global spread of KHV is believed to be linked to the largely unregulated international koi trade.

A presumptive diagnosis of the disease includes observation of high mortality (often 80-100%) among koi or common carp but not other fish species at water temperatures ranging from 18 – 26 degrees C despite treatments to control bacterial infections and or ectoparasite infestations. External pathological signs exhibited by moribund fish include excessive mucus production on the body and gills, swollen and necrotic gill filaments, discolored patches on the gills and skin, and enophthalmos (2,3). Internally, the kidney and spleen may be enlarged. A definitive diagnosis requires the isolation of the virus from infected fish tissues using cell lines of koi and carp origin, followed by polymerase chain reaction (PCR) testing of the isolates. As it is often difficult to isolate KHV via cell culture methods, particularly from decomposed or frozen samples, detection then relies solely on the PCR results obtained from fish tissues. Published PCR assays include single round (9,10) and quantitative tests (11).

Based on the observation that KHV disease is restricted to a temperature range between 18-26 degrees C, a protocol has been developed to produce "naturally resistant" koi (8). Healthy fish are cohabitated with fish dying from the disease for 5 days at temperatures favorable for viral replication and then prior to disease onset are transferred to a non-permissive temperature (30 degrees C) for 30 or more days. These water temperature treated fish develop antibodies against the virus and show improved survival upon re-exposure to the virus. The potential to develop fish that continue to harbor the virus by this method has been a major concern. An additional control method has been pursued by researchers in Israel using an attenuated live virus vaccine (8). Experimental trials demonstrating the irreversibility of the attenuation however, are needed prior to any formal applications of this vaccine. Now that the full sequence of the KHV genome is known, several additional vaccine strategies should be forthcoming.

With the onset of summer and elevated water temperatures our laboratory has recently confirmed the first KHV outbreaks of the year in koi from Northern California. Yearly epidemics in the state (10), serve as poignant reminders of the constant global threat this viral agent poses to both the ornamental koi and common carp industries. Israeli aquaculturists have lost an estimated $3 million annually since 1998 due to KHV epidemics (6). Damages to the Indonesian fishery have reached $5.5 million since the disease hit in 2002 (4). KHV outbreaks in 2003 from two lakes in Japan killed nearly 1,124 metric tons of common carp equaling a net loss of approximately $2.55 million (12). British agencies are concerned that recent fish kills could be the first record of KHV in their wild carp populations potentially threatening Britain’s 3.5 billion pound-a-year angling industry (13). The koi industry has experienced enforced quarantines of KHV positive facilities, restrictions on international koi commerce, cancellation of important koi shows, substantial lawsuits between hobbyists and their suppliers, and untold losses of fish by koi breeders, retailers, and hobbyists around the world.

Literature Cited

1. Bretzinger A, Fischer-Scherl T, Oumouma M, Hoffmann R, Truyen U (1999) Mass mortalities in koi, Cyprinus carpio, associated with gill and skin disease. Bull Eur Assoc Fish Pathol 19:182-185

2. Walster C. (1999) Clinical observations of severe mortalities in koi carp, Cyprinus carpio with gill disease. Fish Vet J 3:54-58

3. Hedrick RP, Gilad O, Yun S, Spangenberg JV, Marty GD, Nordhausen RW, Kebus MJ, Bercovier H, and Eldar A (2000) A Herpesvirus associate with mass mortality of juvenile and adult koi, a strain of a common carp. J Aquat An Health 12:44-57

4. Focus on Koi Herpes Virus (KHV). Fish Health Section/Asian Fisheries Society Electronic Newsletter (2004) Jan./Feb. 3:1-3, accessed at: http://afsfhs.seafdec.org.ph

5. Engelsma MY, Haenan OLM (2004) Global distribution of KHV with particular reference to Europe. International Workshop on Koi Herpesvirus. Accessed at: http://www.frmltd.com/Workshop_KHV.htm

6. Perelberg A, Smirnov, M, Hutoran, M, Diamant, Bejerano Y, Kotler M (2003) Epidemiological description of a new viral disease afflicting cultured Cyprinus carpio in Israel. Is J Aqua Bamidgeh 55:5-12

7. Neukirch M, Kunz U (2001) Isolation and preliminary characterization of several viruses from koi (Cyprinus carpio) suffering gill necrosis and mortality. Bull Eur Assoc Fish Pathol 21:125-1358

8. Ronen A, Perelberg A, Abramowitz J, Hutoran M, Tinman S, Bejerano I, Steinitz M, Kotler M (2003) Efficient vaccine against the virus causing a lethal disease in cultured Cyprinus carpio. Vaccine 21:4677-46849

9. Gilad O, Yun S, Andree KB, Adkison MA, Zlotkin A, Bercovier H, Eldar A, Hedrick RP (2002) Initial characteristics of koi herpesvirus and development of a polymerase chain reaction assay to detect the virus in koi, Cyprinus carpio koi. Dis Aquat Org 48:101-108

10. Gray WL, Mullis L, LaPatra SE, Groff JM, Goodwin A (2002) Detection of koi herpesvirus DNA in tissues of infected fish. J Fish Dis 25:171-178

11. Gilad O, Yun S, Zagmutt F, Leutenegger CM, Bercovier H, Hedrick RP (2004) Concentrations of a herpes-like virus (KHV) in tissues of experimentally-infected Cyprinus carpio koi as assessed by real-time TaqMan PCR. Dis Aquat Org. In press

12. Hall, K (2003) Herpes virus outbreaks that’s killing carp spreads. Associated press Nov. 7, accessed at: http://www.enn.com/2003-11-07/s_10215.asp

13. Meikle, J (2004). Killer disease threatens angling industry. Guardian Unlimited Jan. 4, accessed at: http://www.guardian.co.uk/uk_news/story/0,3604,1119897,00.html

For more information, please contact:
Professor Ronald P. Hedrick, Department of Medicine and Epidemiology
School of Veterinary Medicine
University of California, Davis
Davis, CA 95616

 

 

 

Antibiotic Overdose
By: Charles Lewis

 

     Over the last few years the use of antibiotics in koi by the hobbyist has become common. It has reached the point where many feel they must use antibiotics to heal sores and ulcers in koi. This is not always true. In most cases sores and ulcers can be healed without the use of antibiotics.

 

     Antibiotics can be difficult or illegal to obtain by the koi hobbyist. Injectables need a prescription by a veterinarian and if improperly used can cause more harm then good. Medicated food is difficult to properly administer and has a short self-life. The routine use of antibiotics can also cause resistance and diminish its effectiveness. The fact is that unless bacteria infected the blood of the fish antibiotics are not needed.

 

Most sores and ulcer can be cured with proper care and koi husbandry.

 

     The most common cause of koi and fish health problems is water quality. Ammonia and nitrite can quickly cause health problems that no antibiotic will cure. Antibiotics in the water will compromise biological filtration and make water quality and fish health even worse. Always have fresh and verified test kits to monitor ammonia and nitrite. Use them routinely and when fish show signs of health problems. Often, over feeding, over crowding, or under filtration will cause high ammonia and nitrite problems that can create health problems. The rule of thumb is “Healthy koi need healthy water.” Improved water quality by itself will cure many health problems.

 

     The second biggest health problem is damage caused by parasites. Parasites can be always present or easily introduced. Quarantine and inspection of new fish is always the best prevention for a pond. A pond that has a parasitic outbreak will not get better with the use of antibiotics. Correct identification and treatment of the parasite will quickly reverse problems caused by parasites. Fish that had major damage and sores by parasites quickly heal and get well once the parasites are eliminated.

 

     Wound care can be a simple onetime procedure. Sores and ulcers can be effectively treated with simple first aid. Clean the wound with a topical antiseptic microbicide like Betadine solution, 10% providone-iodine that is available in most drug stores off the self. Then apply a topical antibiotic like Neosporin.  Even without that with improved water quality and the elimination of parasites koi can heal by themselves.

     It is also important to remember temperature. Koi are cold blooded and rely on water temperature for metabolism and immune response. The ideal temp is 70° F to 75° F. Koi under these temperatures will not heal as well and may need to me warmed.

 

     Proper diagnoses, treatment and koi husbandry are more effective in the treatment of health problems then the use of antibiotics.

 

 

 

Koi Health a Field Guide
Ich

By Charles Lewis

 

Ichthyophthirius multifilis also called freshwater Ich is a ciliated protozoan that encysts under the epidermis of the fish and in it’s encysted condition, causes small white spots all over the fish’s body and fins. You may see them under the scope, or exclusively on the gills. In some cases Ich spots will be present but not visible. This is how infected fish get introduced without being detected. Even if quarantined for some time symptomatic carriers can sustain Ich for a period of time. Ich kills rapidly smaller tropical and goldfish but may spare larger fish like koi. This suggests some fish can become immune to re-infection or for a vaccine. Under the microscope Ich looks like a large brown blob with a horseshoe shaped nuclei.

 

The life cycle of Ich is 2-5 days but can live over 5 weeks in cooler water. The parasite has a phase that encysts in the epidermis of the fish and is called a theront. When the theront matures under the skin it drops off becoming a trophont and divides into hundreds of tomites that actively seek out a new host to encyst and cycle the infection. A strain of Ich has been found that does not leave the fish. Safe from medication the trophozoite releases the tomites. The lesion looks much like carp pox.

 

Ich can be prevented and controlled with salt. Add 0.3% salt to the pond this is also 3ppt or approx.1.0 lbs X 3 per 100 gallons. A salt meter or test kit is handy for checking levels. If fish are dying quickly all the salt can be added at once but it is easier on the fish if it is spread over 2-3 days. It will take 3-5 days for the last spot to clear. Despite salting new spots will appear for the first two days. These are the trophonts that managed to get under the skin before the salt was added.  It is recommended to keep the salt at 0.3% for 7-14 days.

 

Fish behavior is an important diagnosis tool. Fish that are agitated, jumping and flashing is a symptom of parasite infection. Excess slime coat production creates foam or bubbles and is an early sign of infection. Early diagnoses and treatment is important. It will prevent further complications with sores or ulcers and mortality.

 

 Aquaculture has much to offer the hobbyist. Their methods are the base
for fish husbandry.  Their industry funds most of the research and development we use.  This article 
is informative but easy to read.  Everything  in it can be applied to  Koi.

Introduction to Fish Health Management

Ruth Francis Floyd

What is fish health management?

Fish health management is a term used in aquaculture 
to describe management practices that are designed to prevent fish disease. once fish get sick it can be difficult to 
salvage them.

Successful fish health management begins with prevention 
of disease rather than treatment. Prevention of fish 
disease is accomplished through good water quality 
management, nutrition, and sanitation. Without this 
foundation it is impossible to prevent outbreaks of 
opportunistic diseases. The fish is constantly bathed in 
potential pathogens, including bacteria, fungi, arid 
parasites. Even use of sterilization technology (i.e., 
ultraviolet sterilizers, ozonation) does not eliminate 
a11 potential pathogens from the environment. Suboptimal 
water quality, poor nutrition, or immune system suppression 
generally associated with stressful conditions allow these 
potential pathogens to cause disease. Medications used to 
treat these diseases provide a means of buying time for fish and enabling them to overcome opportunistic infections, but are 
no substitute for proper animal husbandry.

Daily observation of fish behavior and feeding activity 
allows early detection of problems when they do occur so 
that diagnosis can be made before the majority of the 
population becomes sick. If treatment is indicated, it 
will be most successful if it is implemented early in the 
course of the disease while the fish are still in good 
shape.

The significance of fish disease to aquaculture

Fish disease is a substantial source of monetary loss to aquaculturists. Production costs are increased by fish disease outbreaks because of the investment lost in dead fish, cost of treatment, and decreased growth during convalescence. In nature we are less aware of fish disease problems because sick animals are quickly removed from the population by predators. in addition, fish are much less crowded in natural systems than in captivity. Parasites and bacteria may be of minimal significance under natural conditions, but can contribute to substantial problems when animals are crowded and stressed under culture conditions.

Disease is rarely a simple

association between a pathogen and a host fish. Usually other

circumstances must be present for active disease to develop in a population. These circumstances are generally grouped  under the umbrella term "stress" (figure 1)

Disease

 

 

Figure 1. Disease rarely results from simple contact between the fish and a potential pathogen. Environmental problems, such as poor quality or other stressors often contribute to the outbreak of disease.

Stress is discussed in greater detail in the IFAS publication
"Stress Its Role in Fish Disease". Management practices 
directed at limiting stress are likely to be most effective 
in preventing diseases outbreaks.

Determining if your fish are sick

The most obvious sign of sick fish is the presence of dead or 
dying animals. However, the careful observer can usually tell
that fish are sick before they start dying because sick fish 
often stop feeding and may appear lethargic. Healthy fish 
should eat aggressively if fed at regularly scheduled times. 
Pond fish should not be visible except at feeding time. Fish 
that are observed hanging listlessly in shallow water, gasping
at the surface, or rubbing against objects indicate something 
may be wrong. These behavioral abnormalities indicate that 
the fish are not feeling well or that something is irritating
them.

In addition to behavioral changes, there are physical signs 
that should alert producers to potential disease problems in 
their fish. These include the presence of sores (ulcers or 
hemorrhages), ragged fins, or abnormal body conformation 
(i.e., a distended abdomen or "dropsy", and exopthalmia or 
("popeye"). Once these abnormalities are observed, the fish 
should be evaluated for parasitic or bacterial infections.

What to do if your fish are sick

If you suspect that your fish are getting sick, the first 
thing to do is check the water quality. If you do not have a 
water quality test kit, contact your county extension office; some counties have been issued these kits, and your extension agent
may be able to help you with this. If your county is not 
equipped water quality test kit, call the aquaculture 
extension specialist nearest to you (see the list at the end 
of this publication'. Anyone contemplating commercial 
production of fish should invest in a water quality test kit 
and learn now to use it.  A complete kit can be purchased for 
under $200, and can save thousands of dollars worth of fish 
with its first use.

Low oxygen is a frequent cause of fish mortality in ponds, 
especially in the summer. High levels of ammonia are also 
commonly associated with disease outbreaks when fish are 
crowded in vats or tanks. Separate extension fact sheets are 
available that explain oxygen cycles, ammonia cycles, and 
management of these water quality problems. In general, it is
appropriate to check dissolved oxygen, ammonia, nitrite, and 
pH, during a water quality screen associated with a fish 
disease outbreak.

Ideally daily records should be available for immediate 
reference when a fish disease outbreak occurs. These should 
include the dates fish were stocked, size of fish at stocking,
source of fish, feeding rate, growth rate, daily mortality
and water quality. This information is needed by the 
aquaculture specialist working with you to solve your fish 
disease problem. Good records, a description of behavioral 
and physical signs exhibited by sick fish, and results of 
water quality tests provide a complete case history for the 
diagnostician working on your case.

Professional assistance is available to Florida residents 
through the Institute of Food and Agricultural Sciences 
(IFAS) at the University of Florida, the Department of 
Agriculture and Consumer Services, as well as several private
laboratories. A list of these resources is included at the 
end of this publication.

If you decide to submit fish to a diagnostic laboratory you
should collect live, sick fish, place them in a freezer bag
(without water), and ship them on ice to the nearest facility.
Small fish can be shipped alive by placing them in plastic bags which are partially filled (30%) with water. Oxygen gas can be injected into the
bag prior to sealing it. An insulated container is recommended for shipping live, bagged fish as temperature fluctuations during
transit are minimized. In addition to fish samples, a water 
sample collected in a clean jar should also be submitted.

Types of fish disease

There are two broad categories of disease hat affect fish,
infectious and non­infectious diseases. Infectious diseases 
are caused by pathogenic organisms present in the environment 
or carried by other fish. They are contagious, and some type 
of treatment may be necessary to control the disease outbreak.
In contrast, non‑infectious diseases are caused by environmental 
problems, nutritional deficiencies, or genetic anomalies; 
they are not contagious and usually cannot be cured by 
medications.

Infectious diseases. Infectious diseases are broadly 
categorized as parasitic, bacterial, viral, or fungal 
diseases. Parasitic diseases of fish are most frequently 
caused by small microscopic organisms called, protozoa which 
live in the aquatic environment. There are a variety of 
protozoans, which infest the gills and skin of fish causing 
irritation, weight loss, and  eventually death. Most protozoan infections are relativelv easy control using standard fishery chemicals 
such as copper sulfate, formalin, or, potassium permanganate. Information on specific diseases and proper use of fishery chemicals is 
available from your aquaculture extension specialist.

Bacterial diseases are often internal infections and require 
treatment with medicated feeds containing antibiotics, which 
are approved for use in fish by the Food and Drug 
Administration. Typically, fish infected with a bacterial 
disease will have hemorrhagic spots or ulcers along the body 
wall and around the eyes and mouth. They may also have an 
enlarged, fluid filled abdomens and protruding eyes. 
Bacterial diseases can also be external, resulting in 
erosion of skin and ulceration. Columnaris is an example of 
an external bacterial infection, which may be caused by rough 
handling.

Viral diseases are impossible to distinguish from bacterial 
diseases without special laboratory tests. They are difficult 
to diagnose and there are no specific medications available 
to cure viral infections of fish. The most important viral 
infection that affects fish production in the southeastern 
United States is Channel Catfish Virus Disease, caused by a 
herpes virus. Consultation with an aquaculture or fish health 
specialist is recommended if you suspect a bacterial or viral 
disease is killing your fish. Fungal diseases are the fourth 
type of infectious disease. Fungal spores are common in the 
aquatic environment, but are not normally a problem in healthy
fish. When fish are infected with an external parasite,  
infection, or injured by handling, the fungi can colonize 
diseased tissue on the exterior of the fish. These areas 
appear to have a cottony growth or may appear as brown 
matted areas when the fish are removed from the water. 
Potassium permanganate is effective against most fungal 
infections. Since fungi are usually a secondary problem, 
it is important to diagnose the original problem and correct 
it as well.

Noninfectious diseases. Noninfectious diseases can be broadly
categorized as environmental, nutritional, or genetic. 
Environmental diseases are the most important in  commercial,
aquaculture. Environmental diseases include low dissolved 
oxygen, high ammonia, high nitrite or natural or man made 
toxins in the aquatic environment. Proper techniques of 
managing water quality will enable producers to prevent most
environmental diseases. There are separate IFAS publications 
which address water quality management in management in 
greater detail.

Nutritional diseases can be very difficult to diagnose. A 
classic example of a nutritional disease of catfish is 
"broken, back disease", caused by vitamin C deficiency. 
The lack of dietary vitamin C contributes to improper bone 
development, resulting in deformation of the spiral column. 
Another important nutritional disease of catfish is 
"no blood disease" that may be related to a folic acid 
deficiency. Affected fish become anemic and may die.  
The condition seems to disappear when the deficient feed is
discarded and a new feed provided. Genetic abnormalities 
include conformational oddities such as lack of a tail or 
presence of an extra tail. Most of these are of minimal 
significance, however, it is important to bring in unrelated 
fish for use as broodstock every few years to minimize 
inbreeding.

To be continued....with                 

Behavioral Signs of Disease  

 

Behavioral Diagnosis

Ruth Francis Floyd

Veterinarians are familiar with the importance of behavioral signs in domestic mammals. Changes in behavior frequently offer them clues that direct the evaluation of a problem. For example, an alopecic dog that is scratching extensively will be evaluated differently than one with no signs of discomfort. In this respect, fish are no different than the mammals we are more accustomed to evaluating. Although addressing the clinical significance of behavior patterns displayed by fish may seem novel, for years biologists have used behavioral changes in fish as health indicators in toxicologic and other studies. Veterinarians practicing on fish will benefit greatly by learning to use fish behavior as a diagnostic tool.

 

In natural aquatic systems, behavior provides adaptive mechanisms for fish to maintain themselves in favorable environmental conditions. In aquariums, fish are not able to remove themselves from adverse environmental conditions, and consequently, behaviors become even more important signals that something is wrong. The most difficult thing about using behavioral signs in the evaluation of fish health is that veterinarians are generally unfamiliar with fish. As a result, it is difficult to appreciate normal behavior, much less understand the significance of abnormal or altered behavior patterns. This lack of familiarity with our potential patients is further complicated by the tremendous variety of different species fish ­that we may expect to encounter in practice. Luckily it is possible to categorize a number of fish behaviors and examples of their relationships to clinical diagnosis to serve as a basis for the incorporation of observational fish diagnosis into clinical veterinary practice veterinary practice.

General Considerations

      As in more familiar animals, fish behavior can be both a sign

Of trouble and a cause of trouble. Most behavior that causes

trouble is related to social interaction.. For example aggression

toward tank mates, evidenced by chasing or Fin-nipping can cause

stress‑related disease in the submissive individuals being chased.

Similarly, excessive hiding or rapid escapes can lead to simple

trauma from hitting items in the tank or through inadvertent

departures from the tank. Social Interactions can also interfere

with feeding, causing nutritional problems including starvation or

gluttony. Behaviors not involved with social interactions are less

frequently the obvious, direct causes of health problems, but can

contribute to pathology that would otherwise be in apparent. Pica

(or sand and gravel eating) is a good example. Underlying

physiologic problems may drive the behavior, but the behavior

contributes obstipation and buoyancy problems to complicate the 

case. It is important to recognize the underlying behavioral

causes of these cases in order to successfully treat them.

 

Behavior as a sign of underlying physiologic troubles can be very specific, but most often is dishearteningly general. How these behaviors occur epidemiologically can be important. Anorexia or lethargy indicates general malaise. If all fish in a tank are affected, particularly if several different species are involved, an environmental problem should be suspected as a top differential possibility. On the other hand, if only one or a few fish are affected, infectious disease should receive equal if not greater attention. Therefore, although fish behaviors generally must be interpreted in concert with other knowledge, a sound understanding of what each behavior means is a good adjunct to knowledge about fish diseases.

 

Clinically significant specific behavior patterns of fish

 

Aggression

 

Perhaps the most common problem behavior reported in pet fish is undesirable aggression. Fin‑nipping and chasing are examples of aggressive territorial behavior, and are discussed separately. Many fish are aggressive or territorial only in specific circumstances. Cichlids are a popular group of fish that are particularly noted for their aggressive and predaceous nature in mixed populations, yet young cichlids can be peaceful, schooling and suitable for a community tank. When they mature, however, they often become very territorial and aggressive.

 

Aggressive and territorial behavior can frequently be avoided by mixing compatible species in an appropriate order. Prior residence gives a fish an advantage over more aggressive tankmates that are introduced later=. The addition of sufficient rocks or other structures for the establishment of individual environment niches will also help decrease territorial aggression. This may 'be an effective means of minimizing combatant behavior for extremely territorial species such as the dwarf gourami. Hiding places may be needed for peaceful fish to escape harassment.

 

If certain fish become aggressive enough to cause stress in less assertive tankmates, further intervention may be warranted. One solution to a single aggressive fish is to add numerous conspecifics. This is often effective in improving the disposition of a previously solitary member of a moderately aggressive species such as the swordtails. This can work as well as the more extreme options of removing the offending fish from the tank.

 

For some species, separate housing is the only means c` controlling predaceous behavior. Large carnivores, such as

jack Dempsey and Oscar, can only be housed with larger species whe­n mature. These fish are usually responsible for the mysterious

 

8

 

disappearance of smaller tankmates.

 

Anorexia

 

Anorexia or loss of normal feeding activity can be obvious when a surface feeding fish suddenly refuses food offered. It is more difficult to recognize in a scavenger, which is not fed directly, but feeds on algae or other materials present in the environment. Close observation of these fish may reveal markedly decreased activity or an accumulation of the normal food material for that species, such as algae overgrowth. Loss of condition is also a sign of anorexia and improper feeding activity. Unless fish are observed closely, this is not likely to be noticed until well advanced.

 

Anorexia is a nonspecific sign. It can be due to a variety of problems. Causes of anorexia include handling stress, adverse environmental conditions, and infectious disease. Anorexia may be a normal condition associated with reproductive activity in some fish, but it is more often a general indicator that things are not well. Although nonspecific, the practitioner may be able to ascertain which fish are affected, and thereby gain insight as to what the underlying problems may be. As mentioned earlier, if all fish in the tank are affected, an environmental problem would probably be the first thing ruled out. Another possibility would be the existence of a general stressor (for example, recent handling) that affected the entire fish population. If all members of one species were anorexic but other fish in the tank are feeding well, the husbandry program should be evaluated to determine the suitability of the environment, diet, and tankmates for that species. Housing incompatible species in a tank may result in species‑specific anorexia due to stress associated with aggression. or territoriality. Finally, anorexia exhibited by an individual fish :,r a few unrelated individuals in a tank community is probably best interpreted as an early sign of infectious disease.

 

Bottom-sitting

 

      Resting on the bottom is normal behavior for sedentary species

and fish that are asleep. Examples of fish that are considered to

be sedentary include the plecostomus, bichir, polyterus, lungfish,

Chinese algae eaters, and some of the slower catfish. These fish

are   frequently hidden, they move around very little and some

external stimulation may be needed to stir them up. The leaf fish

is a sedentary species in the sense that it may move around very

little, but its normal position would be in the upper levels of the

water column and not sitting on the bottom. Fish that are asleep

will also lay quietly on the bottom, but the lack of activity will

be specifically associated with dim lighting and a quiet room.

Fish that are suddenly awakened by unusual activity or turning on

the lights during their normal resting period may take time to

rouse themselves. Sleep, and the groggy activity associated with

 

unexpected disturbance, can be differentiated from clinical depression by the return to normal activity within 30 minutes if the lights are left on.

 

Bottom-sitting may be clinically significant if displayed by a normally active species or if the affected fish is one not normally found on the bottom. In this instance, it may be considered a general indication of malaise or depression. Other signs such as anorexia or drifting may be observed. If just one fish is affected, a differential diagnosis of bacterial or parasitic disease should be pursued. If a whole population is affected, the possible contamination of the environment with some toxicant, particularly carbon dioxide, should be investigated.

Circling

Circling is a swimming behavior as opposed to the positional behavior of curling. It is very similar to whirling, but a circling fish has control of its movement. It swims purposefully in moderately tight circles in a limited area of the tank. It can be a sign of unilateral blindness, in which case the good eye will be to the outside of the circle. The blindness may be central or involve the eye. Circling also occurs with unilateral fin damage, and the behavioral change frequently becomes obvious before the 4n damage is recognized.

Color Change

Color chances may be indicated by a fish appearing lighter or darker than normal or there may be a change in the intensity of color. Blind fish exhibit a species‑specific color change, which can be either a lightening or darkening. If blindness ‑‑s suspected, the practitioner should question the owner as to the presence of other behavioral changes such as a decrease in aggressive or schooling tendencies, sitting in a corner, anorexia, failure to find food, reluctance to swim to escape capture, or lack of response to a threat. These are examples of behavioral changes associated with blindness that are easily noticed by the owner. Any of these behaviors could be associated with unilateral blindness, but their expression. would be more subtle than with bilateral blindness.

 

Darkening of a fish occurs secondary to endocrine changes

specifically the release of ACTH or melanocyte-stimulating hormone (MSH). This can occur in association with reproductive activity, stress, or gastrointestinal problems. In the case of stress, wholebody darkening is observed, whereas in the case of gastrointestinal disorders, the head is primarily affected.

Blanching is a marked paleness of decreased intensity of color that generally diffusely affects the whole body of the fish. The author has observed blanching in channel catfish exposed to very 

 

 

 

 

low levels of dissolved oxygen. A specific paleness of the bright horizontal line of neon tetras is highly suggestive of infection with the microsporidian Pleistiphora. this disease has other characteristic signs and is discussed in the section on tail­-walking.

 

An increased intensity in color patterns or the display of new colors may be associated with a change in reproductive status. This is particularly noted in male cichlids, which assume very bright colors when spawning. Normal loss of spawning colors can be interpreted by owners as a blanching or paleness, but is a normal color transition. True paleness can be a sign of discomfort associated with bacterial or viral infection in a variety or fish.

Coughing

Coughing is when a fish suddenly flares its opercular coverings and closes them forcibly, forcing water to rush back over the gills. The normal function of coughing is to clear the gills of accumulated debris'. However, when increased in frequency, it is a sign of gill disease. Protozoan or fluke infestations, bacterial gill disease, and any other conditions that irritate the gills cause coughing.

Chasing

Chasing is the rapid movement of one fish in close pursuit of another. Chasing can be differentiated from normal active swimming because both participants exhibit rapid burst swimming of short duration, with the result of one fish being actively driven away from the other. This is normally indicative of mild aggression. Or ­defense of territory. The dwarf gourami is a territorial species that will commonly chase other fish away from niche it has established for itself. Normal swimming activity for the angel fish would best be described as hovering, yet because of its moderately aggressive nature, it may actively chase more peaceful species housed in the same environment. Chasing is an example of a behavior that is not abnormal, but which tan cause a problem if it is of sufficient degree to stress the fish being pursued. An active fish, such as a guppy or tetra, which is forced into hiding by aggressive tankmates may refuse food and be stressed sufficiently to become susceptible to oppertunistic pathogens in the environment . In this situation, the social structure of the tank community should be evaluated.

Curling

Curling is when a fish assumes a posture in which the body is bent laterally, bringing the tail close to the head.

This may be more of a posture than a behavior, since the fish has no apperent control and is generally moibund.            _ the posture is due to asymmetric muscle firing an is a grave sign. (being there done that).

 

Dorsal fin erection

Dorsal fin erection is the opposite of fin-clamping. It is generally associated with aggression, courting, and other robust activities of healthy fish.

 

Drifting

Drifting is aimless unpropelled motion through the water. Affected fish are very weak and may be buffeted by the current created by an airstone. This gives the appearance of independent movement, but closed observation reveals that the fish is being pushed by water movement. Weakness of this degree is usually indicative of moribund condition. If only one or a few members of a population are affected, infectious disease should be suspected and parasitic and bacterial etiologies investigated. More generalized involvement of the tank population signals severe environmental problems.

 

Fanning

Active fanning of the water with the pectoral fins is most often a reproductive behavior associated with spawning. The water moved by the fins is directed over the eggs. The occurrence of this behavior is often coupled with increased aggression since the spawning fish is protecting eggs.

 

Favoring one side

A fish favoring one side will show only one side to the observer. This swimming behavior is frequently evidence of a unilateral sensory deficit. This is often unilateral blindness, but can include damage to olfactory of lateral line organs. The fish is wary of a potential predator and keeps its functional sensors directed toward the expected hazard regardless of whether the sensor will be effective through the glass. Other signs of blindness are discussed in the sections on color change, seclusion and timidity.

 

Fin-clamping

Holding the fins into the body is a sign: of an unhappy fish. It may represent the early signs of impending disease or be the result of a recent loss in a territorial encounter. This behavior is analogous to a fluffed bird, and is considered a general sign of depression.

 

Fin-nipping

Fin-nipping, like chasing, is an example of aggressive behavior. It can be classified as a problem behavior because the fish that are nipped develop ragged fins and are stressed. Damaged fins and tissue are potential sites for bacterial invasion. As with other problems related to aggressive behavior, the social structure of the tank community should be evaluated. Methods of decreasing undesired aggression were outlined earlier in this article.

  Other important causes of ragged fins should be ruled out when addressing this problem. For example, male Siamese fighting fish have long flowing fins that are damaged by hydrostatic pressure when the fish have access to spacious areas that permit active swimming. Ragged fins can also be caused by infectious disease, particularly ectoparasites, which can be diagnosed by a fin biopsy. When a fish is presented with ragged fins, it is important to determine whether or not the owner has actually observed the nipping behavior or merely suspects aggression.

  Flashing

Flashing describes a fish turning on its side and making a rapid semicircular swimming motion. In the process, the fish will usually rub against objects in the aquarium, including sand, gravel, or rocks. Flashing is a sign of an "itchy,, fish. Ectoparasite infestation is the most common abuse of this behavior, and a skin scraping and gill biopsy are indicated. In cases of severe gill parasitism, the flashing will be directed so that the impact with the substrate is to the opercular area rather than the back. Other signs of ectoparasitism include excess mucus production, and, in severe cases, anorexia.

  Head-standing

Head-standing is when a fish assumes a vertical position. in the water column with its head down. This is a serious sign, indicating loss of control of equilibrium or buoyancy, and is frequently associated with gas accumulating in the abdominal cavity or subcutaneously in the peduncular region. Causes of gas accumulaticn ir. The abdominal cavity include gas-forming enteritis and unilocular swimbladder occlusion in fish with bi-lobed swim bladders. Head-standing is occasionally observed in channel catfish infected with the bacterium Edwardsiella tarda, which is a causative agent of emphysematous petrifactive disease of catfish'. The behavior is caused by large areas of subcutaneous emphysema which, when located on the caudal and lateral aspects of tie peduncle, cause the tail stalk to protrude from the water surface, preventing the fish from swimming normally.

Hiding

A fish that is hiding will position itself among vegetation or under some structure so that it is less visible to observers or other fish. This is a normal behavior for some shy or sedentary species and for fish that are protecting eggs or young. 1t may

also be a normal behavior for a newly introduced animal that feels threatened by new surroundings. From the clinical perspective, hiding must be differentiated from seclusion, which is a sign of disease and is discussed later in this article. The normal fish that is hiding should display normal orientation and movement. The physical appearance and respiratory rate should be within normal limits. A newly introduced fish might be anorexic for a few days as it adjusts to the change in environment but, if healthy, should resume normal feeding and other behavior patterns within a short period of time. A fish that is hiding because of excessive harassment from more dominant tankmates may be stressed, anorexic, and more susceptible to opportunistic pathogens. Such a fish may be differentiated from an unstressed fish by darkened coloration, and it may be observed fleeing back to its hiding place when attempting to feed or interact with other fish.

Hovering

Hovering is a swimming pattern in which fish stay relatively in one place in the tank and water column when interacting with people or not being pushed to move. This is normal behavior for angel fish, hatchet fish, Siamese fighting fish, and some of the fancy goldfish.

Hurdling

A fish that is hurdling will be observed falling and then suddenly spurting forward and gaining vertically in to water column. This behavior is similar to darting except that the fish is very depressed and is actually drifting in the down phase. This is a sign of neurologic problem, which may be associated with ­ammonia toxicity, some other environmental toxicant, or an infectious agent that has gained access to the central nervous system.

Inverted swimming

A fish that swims upside-down should be observed closely to determine if it is capable of righting itself because some fish do this normally. The author has observed one instance in which inverted swimming was a learned behavior that enabled a small channel catfish, a bottom feeder with a ventrally located mouth, to compete successfully with more aggressive surface feeders in a home aquarium.

Observance of the position in the water column and physical appearance are helpful in determining the cause of inverted swimming. Upside-down swimming in which the fish is at the surface and unable to submerge or right itself is often caused by an accumulation of gas in the abdomen. or intestine. Gas bubble disease is a recognized syndrome in which affected fish are housed in water that is supersaturated with dissolved gas. Although 

 

gaseous emboli may form in other locations, the classic presentation is when the abdomen is grossly distended due to an accumulation of gas in the peritoneal space, which causes the fish to swim with the affected area protruding from the water surface. Enteric bacteria such as Edwardsiella ictaluri may cause gaseous enteritis, which may also result in upside‑down swimming at the surface'. In these cases, the abdomen may not be grossly distended, but necropsy will reveal that the intestine is markedly distended with gas.

 

Subcutaneous emphysema such as that in Edwardsiella tarda infection will cause the affected part of the body to float at the surface. Observation will confirm the inability of the affected fish to submerge.

The concurrent display of inverted swimming with other signs of disorientation such as whirling or circling is an indication of neurologic impairment. This type of swimming would not be confined to the upper regions of the tank since no gas accumulation is involved. If all fish in the tank are affected, ammonia intoxication should be suspected. if one individual is affected and other inhabitants appear normal, consideration of an infectious etiology would be appropriate.

Jumping

Jumping may be an exaggeration of darting or it may be an attempt to escape. Some species of fish are more likely to jump (as a normal activity), and for these species, it is important to keep the tank properly covered. Examples of fish that might categorized as jumpers are guppies, black mollies, and swordtails. Normal fish of any species may occasionally break the surface of the water when startled or in predator-prey situations. In many cases, jumping represents an attempt by the fish to remove itself from adverse environmental conditions such as low dissolved oxygen, inappropriate pH, or the presence of an irritating chemical such as copper. Such fish may swim frantically and try to get out of the water. All fish in the tank would be affected by an environmental problem.

Lethargy

A decrease in, or complete lack of, normal activity can be an important nonspecific sign that a fish is not well. A review of the clinical history is indicated to confirm that the aquarist has not mistaken normal periods of rest with an abnormal state. Some species of fish may sleep, particularly at night when lights are low and there is little noise or activity to disturb them. Sleep can be differentiated from lethargy by the relatively rapid resumption of normal activity when lights are left on. C1inically significant low water temperature, overfeeding, or if diseased, the fish would be expected to exhibit other signs such as weakness, anorexia, or drifting.

Piping

Gulping air at the surface of the water is frequently referred to as piping. Piping is an abnormal behavior that is indicative of severe hypoxia. The hypoxic fish is distressed and may show signs of trying to leave the water, such as jumping. Piping represents an effort by the fish to utilize oxygen from a thin surface layer of the water that is supersaturated with dissolved atmospheric oxygen. It is important to clinically differentiate this important sign from several normal behavior patterns.

Three normal behavior patterns might be confused with piping. First, some fish are air breathers and are able to utilize atmospheric oxygen from the water surface. For them, piping is a normal behavior and there should not be any evidence of stress. These fish would not be expected to remain at the surface gulping for prolonged periods, nor would any mortality be expected. Examples of air breathers are lungfish and some eels. Second, surface-dwelling fish (such as the leaf fish) might be confused as displaying piping behavior because prolonged periods of time may be spent at the surface. Close observation will reveal that these fish are not distressed and are not actively gulping air. Finally, the bubble-nests are a group of fish that utilize atmospheric gases to construct nests. These fish swim repeatedly to the surface and carefully build nests of bubbles that serve as a site for egg deposition. Examples of fish in this group are the Siamese fighting fish and some of the gouramis. This normal behavior can be differentiated from clinically abnormal behavior by the lack of anxiety in affected individuals and by the fact that they are concurrently engaged in other activities associated  with,  nest­building.

Hypoxic conditions indicated by piping  may be due to low levels of dissolved oxegen in the water or to physiologic abnormalities that interfere with the use of available oxygen. Testing the water for oxygen content is discussed in the article "Evaluating Water Problems." High levels of nitrites, also discussed in the article, can cause methemoglobinemia. As in domestic animals, methemoglobinemia causes the blood to take on a chocolate brown color and the hemoglobin molecule is unable to effectively transport oxygen to the tissues, resulting in physiologic anoxia.

 

Gill parasites can disrupt the uptake of oxygen by causing a mechanical blockage of the gill filaments. The amount of actual tissue destruction that occurs varies with the species and the degree of infestation. When piping is evident in the presence of acceptable water quality, a gill biopsy is indicated. 

Anemic conditions may cause sufficient hypoxia for the fish to display piping behavior. If anemia is a result of bacterial disease, other physical or behavioral signs (for example, depression) may be evident. A severe anemia of undetermined etiology has been reported in channel catfish. Affected fish display active piping behavior in the presence of high levels of dissolved oxygen. Although not reported in pet fish, it might be considered on a differential if an extreme anemia was observed in the absence of any other abnormality.

Schooling

Schooling is a social characteristic displayed by some species of fish that swim in large numbers as an aggregate unit. Schooling fishes can be differentiated from other fish that live in closed proximity to conspecifics by the uniform geometric orientation maintained by the school. The most commonly kept pet fish that display this characteristic are the tetras. Schooling fish may disperse when startled or during feeding periods. The lack of schooling behavior in fish that normally display this characteristic may signal disease, particularly if only one fish is affected, or an environmental problem if the entire population is affected.

Seclusion

A fish in seclusion is alone and avoids interaction with other fish. The fish may or may not also hide. Such a fish may be lethargic and swim slowly at the periphery of the tank, frequently near the surface. This is a sign of serious illness, which is frequently infectious in nature. A complete clinical evaluation, including skin and gill biopsy, bacterial cultures, and, in some cases, viral cultures, is indicated. An exception to this generalization is a blind fish that Fairs to school normal because of the lack of visual stimulation', and sits in a corner. Blindness is discussed in greater detail in the section on color change.

Tail-walking

Tail-walking is a swimming movement in which the fish does not swim in a normal horizontal plane, but assumes an oblique position with the head directed toward the surface. The behavior is characteristic of tetras infected with the micresneridian Pleistophora. Abnormal positioning by the affected fish is due to loss of control over equilibrium, and it may appear to swim backwards as it attempts to correct its posture. Other behaviors associated with Pleistophora infection include continuous swimming, a failure to assume normal sleep patterns, and a lack of schooling activity. Definitive diagnosis of the disease is best achieved through histologic examination of muscle tissue. The organisms encyst in the tissue, and affected areas are characterized by liquefactive necrosis. Although this disease is most frequently reported in neon tetras, it has also been reported in members of the families Characidae and Cyprinidae.

Timidity

Timidity is the demonstration of fearful or shy behavior. This is a relative term. In generally nonaggressive fish, it may be evidenced by hiding or seclusion, which have already been discussed. Nonaggressive species (such as guppies) that are housed with relatively more aggressive species (such as tiger barbs, swordtails, or angel fish) may become timid because of excessive harassment. In such a situation, the aggressors may be observed chasing or nipping the more peaceful fish. Chasing and fin-nipping can cause stress in the submissive fish and related stress problems can result, as has been discussed.

Normally aggressive fish that suddenly become peaceful should also be considered timid. Blind fish exhibit less aggression and territoriality than normal for their species because of an inability to respond to visual cues. These behavioral changes will be less pronounced in a fish that is unilaterally affected because of compensation.

Voracity

Voracity is the ravenous consumption of large amounts of food. This is normal behavior for goldfish, which are similar to horses in the sense that they continue to feed beyond the point of satiation. Goldfish, and probably any fish, should be fed a predetermined amount based on a restricted feeding time or per cent body weight. Overfeeding can cause problems because of deterioration of water quality, which will endanger all tank residents.

Whirling

Rapid uncontrolled whirling was first described in salmonids infected with whirling disease caused by the sporozoan parasite Myxosoma cerebralis. The behavior is a frenzied, tail-chasing movement, which is most frequently observed when fish are fed or startled". Other signs of the specific disease in salmonids include a darkening of the peduncle and caudal fin and skeletal deformities that become apparent as infected fish mature. Whirling disease in saimonids should be considered a reportable disease ,and procedures for identifying the organism anal handling suspected outbreaks are detailed in the Fish Health Blue Book published by the American Fisheries Society. In pet fish, whirling is mere likely to occur because of neurologic deficits secondary to ammonia intoxication. or infectious disease.

Coming next: Stress-Its role in fish disease.