Causes of Guppy Diseases

Disease is present in all ecological systems, and a very old contest between microscopic enemies and higher order animals continues unabated to this day. In fact our immune systems are stimulated by the presence of pathogens, and if we were raised in a completely antiseptic environment we would be extremely vulnerable to disease as soon as we left it.

These show guppies are hanging near the surface of the bowl where the oxygen is the
most abundant.The sudden change in water conditions has stressed them. When they
are returned home, it's a good idea to isolate them until it's clear they have not developed
a disease.

You may think that the closed ecological system of your crystal clear aquarium with its newly cleaned filtration system is free of disease, and you can keep it that way, but this is a mistaken notion. To begin with, a tank is at a disadvantage to a natural body of water. The fish population in a tank is at a much higher density than in the wild, and the fish are totally dependent on your sanitation and feeding regimes.

Bacteria, fungi and parasites are present in every aquarium, even the cleanest, arriving on the guppy's scales and in its intestines, and hitching a ride on your hands and nets. There are types of live and frozen food (e.g. bloodworms) that raise the risk of the introduction of disease to your tanks, diseases for which your guppies have not yet developed immunity. Even the dry food you sprinkle on the surface of the water contains the seeds of future disease outbreaks.

So the proper focus of a guppy disease management program is not listing cures for disease, but prevention of disease in the first place. If the fish is diseased, it's probably already too late for treatment. The foundation of any program of guppy health is good water quality management, careful introduction of new fish to your tanks, proper sanitation and nutritious food fed judiciously.

There are no magic bullets for disease prevention. Some hobbyists resort to sterilization technology, such as ultraviolet sterilizers, but these are not completely successful. Adding chemicals to tanks to prevent disease usually adversely affects the biological cycle, exposing fish to ammonia or nitrate poisoning.

Once the guppy develops symptoms of a disease, treating them with chemicals often buys time while the fish uses its own immune system to ward off the disease, but soon plunge the unhappy aquarist in a vicious circle. The hobbyist delves into the fish medicine cabinet to use medication to ward off disease, but the medication upsets the biological cycle, creating the conditions for a fresh disease breakout.

If you have any chance at curing fish diseases, it is in the first two to three days of the onset of symptoms. Clamping disease, for example, is sometimes curable if you catch it right away. After three days, you should probably practice euthanasia on the tank's inhabitants, and bleach the tank.

Early detection requires that you examine your fish when you feed them or clean their tanks. Later we will list some common symptoms. However, the longer you keep guppies, the quicker you will get at diagnosing problems. Certain tank conditions, such as cloudy water, can sometimes give you advance warning.

Guppy breeders have favorite treatments for diseases. Some diseases have obvious symptoms that make the course of treatment equally obvious. Most diseases, however, are far from obvious. A bloated guppy is often treated for dropsy when constipation is the problem. Dr. Jim Alderson, the veterinarian and champion guppy breeder, generally recommends a drug cocktail, something he found effective when treating horses and then applied to guppies. The advantage of a drug cocktail is that it allows more room for error in your diagnosis. Even when your diagnosis is correct, some strains of bacteria have developed resistance to certain fish medications.

Some guppies will die in your aquariums because of a congenital condition. You will occasionally find a dead guppy and have no clue to what killed it. Losing one or two guppies in a sixty tank room should not be cause for too much concern. Disease is a fact of life for guppy breeders. No matter how carefully you do manage your tanks, an extraneous factor like diseased food, will eventually strike at least one tank. In other articles we will alert you to some of the symptoms of fish disease, provide diagnostic clues as to cause, and suggest courses of treatment. However, if you have chronic problems with guppy disease, the first place to look is in your water conditions. And the prime suspect should be your feeding practices.

Guppy Hardiness

According to anecdotal evidence, guppies today are a lot less hardy than they were several decades ago.

This store bought guppy's closed fins and thin body is an early sign of disease.

There are three main factors that account for the decline in guppy hardiness over the past century. One is intensive inbreeding. The guppies chosen for breeding are judged on their visual appearance and not their ability to resist disease. In the natural world, weak and disease-prone wild guppies are quickly consumed by predators. They rarely live long enough to contribute to the gene pool. Guppy breeders do not follow Mother Nature’s book here. Often they prop up their prized but disease-prone guppies with medications, allowing them to pass on their frailty to the next generation.

A second factor contributing to the decline in guppy hardiness is the reliance on medications to solve fish health problems. It’s a problem in human health as well. We are addicted to drugs, preferring the cure to the labor intensive regime of prevention. One of the outcomes of the reliance on medications is new and virulent forms of bacteria and medication-resistant parasites.

A third factor has been the globalization of the fish hobby and the transport of guppies by airlines. Arriving from far flung places are fish with viruses and bacteria that local guppies have developed no defenses against. Many of the most virulent diseases striking guppies today come from tropical regions with indigenous strains of bacteria, viruses and parasites. Our guppies often do not have immunity to these diseases.

Keeping guppies healthy is a severe test of a novice breeder’s initial resolve. Even somebody who has successfully bred and raised other fish may find that raising show guppies on rich diets extremely challenging. Putting size on guppies by feeding them beyond their maintenance and growth needs puts waste into the aquarium. The plan for dealing with the waste will ultimately determine the fate of the guppies. The negative outcome is stunted, deformed or dead guppies. Fancy guppies require constant and intensive care.

Disease Defense Systems

The guppy has certain natural defenses against disease.

1. The inflammatory system normally protects the body against invading pathogens (bacteria, viruses and parasites) through a cellular response marked by redness, swelling or loss of function. The invader is surrounded and isolated. The gills are an important site of infection and often provide a clue that your guppies are under stress when they appear inflamed.
2. Antibodies are a kind of educated response to invading proteins or pathogens. When the guppy is first exposed to an invasion, it produces special molecules to combat the invaders. It stores these antibodies and mobilizes them during subsequent invasions. This is why it is important not to create sterile conditions for guppies. They require a low level presence of pathogens to stimulate production of antibodies.
3. The guppy has a mucus layer on its body that provides a first layer of defense against invading pathogens. It contains lysozymes (enzymes) and immunoglobulins (antibodies) which can kill invading pathogens. It also performs a function in osmoregulation. It helps maintain the normal electrolyte balance (sodium, potassium, chloride). The mucus layer also provides the guppy with lubrication while it swims. Products such as Kordon's PolyAqua, or other products that stimulate or protect a fish's slime coat, are valuable in enhancing the natural protectiveness of the guppy's slime coat.
4. Guppy scales and skin act as a barrier to the environment and protection against invasion by pathogens. The Aquarium Pharmaceuticals product Melafix is a valuable addition to the guppy medicine chest as it helps speed up the healing of superficial wounds that provide an opening for pathogens.One defense system that is not available to guppies is the ability to flee conditions that compromise its defense systems, such as high levels of toxins in the water.

Guppy Stress

While healthy guppies, like healthy people, are susceptible to virulent and infectious diseases for which they have no immunity, most other diseases are indirectly caused by stress. Stress leads to an impairment of the guppy's normal disease defense systems. Stress can be defined as a physiological state the fish enters into in as it prepares for flight from a threatening situation. The threatening situation can be toxins in the water, loud sounds, or a high density of pathogens in the tank. The adrenaline system prepares the guppy for flight from the threatening situation. But it has nowhere to run.

Let's look at what happens when a guppy is stressed:

1. The adrenal gland begins pumping hormones that facilitate an increase of blood sugar. Sugar is metabolized to create an energy reserve for sudden action.
2. Reserve red cells are released into the blood stream.
3. Respiration increases, blood pressure increases.
4. Mineral metabolism disrupts the normal relationship between a guppy's body and environment. The disruption in osmoregulation causes the guppy to absorb more water. It over-hydrates. It attempts to compensate.
5. The inflammatory response is suppressed by hormones released by the adrenal gland, lowering the guppy's defenses against opportunistic pathogens.The guppy may not immediately appear to be stressed, as it draws on reserve energy to maintain equilibrium. However, these reserves are soon depleted and the guppy begins to show overt signs of distress. This is the reason why the guppy should be relieved of stress as quickly as possible. The fish is not in balance with its environment and cannot maintain its normal physiologic functions.

Correcting Stressful Conditions

Almost all guppy diseases are preventable, even those infectious diseases that strike healthy guppies. In this section we'll look at the most common conditions that expose guppies to disease.

The leading causes of stress that are guppy-specific include:

Sudden Changes in Water Conditions

The guppy is adaptable to a wide range of water conditions, including such parameters as pH and GH, as well as water conditions unfavorable in other respects, such as high organic pollutants. However, when conditions are not ideal, the guppy's resistance to disease is lowered and any sudden change can quickly bring on a disease outbreak. Changes to water conditions must be made very slowly. A guppy that arrives from water conditions quite different than your local conditions should be kept at its original parameters and gradually adapted to new parameters over the course of a month. This is especially true when adjusting values down, such as pH 7.9 to pH 7.2. Generally, changing conditions back to the values that the guppy is adapted to can be made more rapidly than changing values away from those values.

Water changes are always stressful, to a degree. As a rule, water changes should be limited to 30% a day, once or twice a week. A water change of 10% a day will not harm guppies. The replacement water should be matched to the parameters of the existing water. Water from the tap should be conditioned and aerated for a day.

Biological Stressors

Both pathogenic and non-pathogenic organisms can be biological stressors. Over time the guppies in your tanks build up natural immunity to the pathogens that are ever-present in the tanks. Introducing new guppies into your fish room introduces new pathogens, and new versions of existing pathogens.

This guppy is suffering from columnaris. If even one guppy in the tank looks like this, assume the entire tank is infected. Columnaris can be very infectious.

All new guppies that arrive in your fish room should be strictly isolated. Place them in their own tanks, and avoid getting your hands wet with the new arrival's tank water. Cleaning should be conducted with separate equipment and you should wash your hands before cleaning other tanks. Certain parasites, viruses or bacteria can spread in a drop of water.

When new fish arrive in our room, we follow a standard procedure for introducing the fish to its new tank, outlined elsewhere in this book. If your water conditions differ significantly from the water the fish came from, there is a danger that the fish will be under constant stress in the first month. It will be susceptible to bacteria or parasites it arrived with, or bacteria or parasites from your fish room or in the food that they are fed. Feed the fish sparingly and do regular, extra water changes to ensure it has the best chance of surviving the period when it must adapt to local water parameters.

The quarantine period should be one month.

Pathogens are present in every aquarium. When the levels of organic pollutants rise, the pathogens that feed on these pollutants multiply. Eventually they become so numerous, they are able to overcome the guppy's natural defenses.

Chemical Stressors

Chemical pollutants can either instantly kill your fish when they are introduced, or gradually reduce their resistance to disease. Included in this category must be medications that are designed to treat diseases. We include them here because they often damage the guppy's mucus layer, removing the guppy's first line of defense against disease. This is why medications should be used sparingly and only as a last resort. The focus should be on prevention, not cure.

Other types of man-made chemicals are hard to detect as they may be airborne or in the water in concentrations hard to measure. They may be introduced with a new gadget you have installed in your tank or water system. If you use well water, the pollutant may come from a nearby farmer's field. Sudden and unexplained deaths are often caused by chemical agents. Insect sprays or ammonia cleaning solutions are examples of chemical stressors.

Never introduce objects or liquids into your water system whose composition you are not sure about. Rocks, for example, may contain soluble minerals or metals that gradually build up to toxic levels. Wash your hands thoroughly before feeding the guppies or cleaning the tanks. We use a water reservoir and let water aerate for twenty-four hours before adding it to our tanks. This ensures that volatile gases leave the water before guppies are placed in it.

We use a water conditioner, even though it is not technically required, as chlorine leaves aerated water within twenty-four hours. For a few cents, why risk your guppy's health?

Poor Water Conditions

By far the biggest cause of guppy illness is poor water conditions. And the biggest contributor to poor water conditions is poor feeding practices. Crowding is another contributor. Poor water conditions directly affect the guppy's immune system, lowering its resistance to disease. A major infection point is the gill filaments, which swell when organic pollutants irritate them, adversely affecting the guppy's ability to breathe. But other organs are under attack, like the kidneys. The slime coat may become damaged through handling or the guppy may not produce enough slime to ward the rise in numbers of parasites or bacteria. Regular water changes and feeding lightly often will help keep water conditions stable and healthy for guppies.

Signs that your water conditions have deteriorated are:

1. Excess amount of feces on the bottom of the tank.
2. Cloudy white or turbid water.
3. Sudden and unexplained deaths.
4. Guppies show sign of stress, hanging near the surface, hiding, lethargic or hanging in one spot.

Sudden guppy deaths may be caused by injury to the fish when cleaning or by chemical pollutants. However, ammonia spikes must also be suspected. Ammonia spikes occur when the nitrogen cycle breaks down or becomes overloaded. The bacteria just can't process the fish waste fast enough.

When guppies hang near the surface, it is an indication that they are having trouble getting enough oxygen. Their gill filaments may be irritated, or the water may be oxygen-poor. The cause may be high levels of other pollutants in the tank. At least 5 mg/L (or 5 ppm) of dissolved oxygen should be in the water to help the guppy maintain its metabolic processes.

You must take immediate action when the guppies look stressed. Damage to the gill filaments can be permanent, so you should alleviate the condition right away. Once parasitic or bacterial infections get established they are hard to defeat with medications.

Incorrect Water Parameters

Putting organic pollutants aside, the water can have the wrong parameters. Although guppies can be adapted to water parameters at the extreme or even beyond the parameter limits, the guppy's health will become fragile. Very soft water may be deficient in some of the minerals required by guppies, and will adversely affect the guppy's osmoregulation. Minerals may leach from the body and the guppy's internal system will have to work hard to compensate. Acidic water will break down the guppy's first line of defense of disease, the slime coat. One of the biggest causes of stress is temperature fluctuations or temperatures at the extreme of the guppy's tolerance. Swings in temperature greater than 10 degrees a day will exceed the guppy's ability to cope. High temperatures cause metabolic rates to increase exponentially, causing food conversion to become poor and inefficient. Cold temperatures, especially when the drop in temperature is swift, can slow down or stop the distribution of antibodies, removing an important weapon in the guppy's disease defense system.

Poor Diet

There are a number of diseases that are the result of nutrient deficiencies, many of them listed in our Nutritional Table in the Tools and Tables section. For example, if your guppies are not getting enough Vitamin C, their resistance to disease will be lowered and their ability to heal wounds adversely affected. Feeding a diet too rich in poor quality protein leads to retarded growth and fat or chesty guppies. Poor quality protein is burned as energy and deposited as fat. This shortens the guppy life. However, be judicious in the use of vitamins. A well-balance and high quality diet will supply the vitamins and other nutrients required by the guppy, making the addition of vitamins to the food unnecessary. At high concentrations, vitamins can actually adversely affect guppies.

Physical Stressors

Loud sounds, continuous light that is too bright, rough handling, shipping, and disease treatments can physically stress guppies.

Summary

Poor water quality and poor quality food are probably the leading causes of guppy disease. A guppy fed on a poor diet is less able to tolerate poor water conditions. Poor water conditions lead to stress, which lowers the guppy's ability to cope with ubiquitous disease. Once the pathogens gain the upper hand, medication can do little to save the guppies. If the disease persists in the aquarium for longer than three days and most of the tank's inhabitants are affected, it is probably best to cull them and sterilize the tank.

If pollutants and pathogens in the tank are high, and the irreplaceable guppies are showing signs of distress, move the guppies to a cycled tank and treat with Formalin and Melafix. By cycled tanks, we mean a tank that has a functioning nitrogen cycle. Do not do this if there is a significant difference in pH or GH values, or adjust the new tank to the existing tank's values and then gradually change the values (over a day or several days) to the optimum values. The logic behind moving the guppies to the new tank is that it will contain a much lower level of pathogens or pollutants, giving your guppies the opportunity to recover and rebuild their immunity.

So far, we've focused on identifying those conditions that give rise to stress, with an emphasis on correcting them. However, occasionally a tank in the fish room does go become diseased, not matter how good your management practices have been. In this last section, we'll paint the disease picture with broad strokes.

Broadly speaking, there are two categories of diseases that affect guppies: infectious and non-infectious.

Non-Infectious Diseases

Non-infectious diseases include environmental conditions (man-made toxins in the tank), genetic deformities, and nutritional deficiencies. They are not contagious and cannot be cured by medicines. A lack of Vitamin C in the diet can lead to poor bone development and such conditions as a deformed spinal column. Genetic abnormalities include a deformed mouth, a Siamese twin, and a bent spinal column. Partially changing water that has not be treated with a chlorine neutralizer can damage the guppy's delicate gill filaments.

Infectious

Infectious disease in the form of pathogens is present in the water, on other fish, and in the foods we feed guppies. Many commercial foods are made from other aquatic organisms, and sometimes they are made from diseased organisms. Dr. Alderson did a study of commercial fish food several years ago and found only one that was free of pathogens, Tetra-Min. Unfortunately past performance is no guarantee of present performance. Infectious diseases can be further subdivided into bacterial, viral, parasitic or fungal diseases. One of the problems in treating guppy diseases is that a fish can show a variety of symptoms that lead to erroneous diagnoses. For example, a bloated guppy may appear to have an internal bacterial infection when it is actually constipated. Treating a tank with antibiotics in an attempt to "cure" constipation can damage the nitrogen cycle, leading to a spike in ammonia, and stressed or fish that develop other diseases. Often one disease can make the guppy susceptible to another, and suddenly you have intermingled symptoms For example, parasitic flukes move across the guppy's skin in a looping fashion, using its hooks and leaving small puncture wounds The punctures open the way for aeromonas bacteria.

With that proviso, we'll try to sort out some broad indications of the type of disease your guppy has.

Bacterial

Fish infected with bacterial diseases will often show ulcerations on the body, or hemorrhagic areas, especially around the eyes or mouth. Fluid often fills their abdomen from internal infection, giving them a bloated appearance. Eyes may protrude.

Viral

Viral diseases share many of the same symptoms as bacterial infections. They cannot be medicated.

Parasitic

Parasitic diseases are caused by tiny protozoa, some barely visible to the human eye. The fish typically flash, attempting to rub the irritating parasites off their skin. Parasites also attack the gills. Emaciation is often a sign of internal parasitic infection. Parasitic infections are easy to cure with such treatments as formalin and potassium permanganate, and medications specific to parasites. Used moderately, these medications do not harm the nitrification process.

Fungal

Fungal diseases often only appear as a secondary infection to another type of disease, sprouting from wounds. Fungal spores are always present in the tank, and dead fish are soon covered with fungus. On live guppies, fungus often appears where the fish has been injured or at the site of a bacterial or parasitic infection. White, cottony growth appears. Potassium permanganate is effective against most fungal diseases.There are medications and treatments that are specific to these different types of diseases. Unfortunately you can rarely rely on the manufacturer's bottle label for information about a medication's effectiveness against a specific disease.