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Are Your Fish Really Suffering From Disease?

A guide to non-disease causes of illness


You have a fish, or several fish, that appear sick. They are scratching against decorations, lethargic, unusually nervous, or gasping at the surface of the water. Clearly, something is wrong! But before reaching for your prefered medication, stop for a moment, and evalulate the situation. If there are no outward signs of disease (white spots, cottony growths, red streaks, etc) your fish may not be suffering from an infectious disease at all.

More often than realized, seemingly sick fish are actually suffering from some negative environmental conditions or introduced toxins. While many of the substances in our daily lives do not affect us adversly, it must be remembered that fish live within their medium. Any foreign substances that enter the tank can and will be breathed in, swallowed, or even penetrate the skin, causing poisoning.

Many of the symptoms we so often associate with disease are in reality general symptoms that can have more than one cause. For instance, there are indeed a few diseases that can cause flashing (scratching) in fish, but there are also many toxic substances that can cause the same behaviour. Flashing can be equated with coughing in people. You may cough when you have a cold, but you may also cough if you walk into a smoky room. It's simply a sign that your lungs have been irritated. The same applies to the gills of the fish.

Please take a quick look at the other possibilities presented on this page before you treat your fish for an uncertain disease. A brief list of symptoms, an explanation, and a recommended course of action is offered for each circumstance.



Before beginning please note:

- Fish that are showing clear signs of a specific disease should be treated immediately with the appropriate medication. This list is only intended to help track down potential problems when the cause of certain symptoms is not clearly diagnoseable. Be aware that in the early stages of many diseases, outward signs may not yet be visible.

- Fish exposed to toxic substances or conditions may, during or after exposure, develop disease due to stress and lowered resistances. Treat if necessary.

- It is assumed that the reader has a basic knowledge of the aquarium hobby. If you are completely new to the hobby, please familiarize yourself with standard auqarium practices.

- Underlined passages indicate fairly diagnostic symptoms of specific health issues, or other important information.

- For your convinience, a brief dictionary of terms is included at the bottom of the page.


Click on the topic of interest or scroll down the page to read the whole article.

Water Quality Issues

Breathing Issues

Introduced Substances


Other Issues






Symptoms: Too hot - Gasping at the surface, flared gills, lethargy, loss of color, sometimes redness at the base of fins. Too cold - Clamped fins, shimmy, deep irregular gasping at any water level, loss of color.

Cause(s): Improper temperature.

Course Of Action: *Slowly* raise or lower the temperature as needed. To raise the temperature, use an aquarium heater. (Never add hot water directly to an aquarium! You can burn the fish and crack the tank!) To lower the temperature of the tank, do a water change using cool water. Add the cool water very slowly and in small amounts, and add the water in the center of the tank (to avoid cracking the glass).

During summer hot spells, use ice cubes securely wrapped in a plastic bag, or for larger tanks, 2 litre pop bottles that have been frozen with water, to keep the tank cooler. (Again, keep these in the center of the tank to avoid cracking the glass.) Check the tmeperature often to ensure against a too quick temperature change.

Please note that not all fish necessarily require the same temperature, so it is best to inform yourself before purchasing new tank mates.


Water Quality Issues


Acidosis/Alkalosis (High or Low pH)

Symptoms: Flashing, gasping at the surface, clamped fins, shimmy, extreme restlessness, excessive jumping, reddened gills, fins and body may become blood-streaked or shredded.

Cause(s): Over-treating the water to reach a desired pH using pH-Up/Down type products, improper or unfinished cycling, overfeeding, overcrowding, decomposition of plants or animals, addition of pH altering objects such as certains rocks, peat, driftwood, or well water.

Course Of Action: Immediate water change (at least 50%, more is better). New water should be added slowly to allow the fish time to adjust to the new pH value. Removal of any pH altering substances. Vaccum the substrate to remove excess food and accumulated debris and waste. Provide vigorous surface aeration. Daily pH verification and water changes should be performed until the situation stabilizes.



Toxic Nitrogen Compounds (Ammonia, Ammonium, Nitrite, Nitrate)

Symptoms: General illness symptoms. Rapid breathing, usually at the surface of the water. Shimmy. Quick darting movements at first, followed by lethargy as the fish begin to die. Fish coloration appears either normal or more intense until after death. Gills may turn red or bloody, and are said to turn "lilac"from Ammonia poisoning, probably meaning that they often don't become fully red or bloodied.

Cause(s): Improper biological cycling of the tank. Excessive amount of fish or other inhabitants in aquarium, or fish stocked too quickly. Insufficient water changes. Decomposing organic matter (uneaten food, dead fish, etc). Destruction of beneficial "cycling" bacteria through the addition of medications or other compounds, or due to clogged or broken filters. Drastic pH swings. Tapwater containing Chloramine (Chlorine joined with Ammonia), especially when Chlorine only neutralizers are used.

Course Of Action: Daily water changes should be performed until the biological cycle re-establishes itself. Adding charcoal or activated charcoal can be of some benefit during the interim. Ensure that filters are functioning properly and do not become clogged, inhibiting current flow . Reduce fish load if the tank is overcrowded or stocked with sensitve species. Frequent testing for these compounds is recommended to spot any rise in levels early. (All levels should read zero, except for Nitrate readings, which are acceptable up to 30 ppm. Any higher reading for any of these substances can be toxic, though some fish species are more resistant than others.)


Symptoms: Flashing. Gasping. Rapid breathing. Red gills. Pale body colour. Body may appear rough and irritated. Fish usually die with gills wide open.

Cause(s): Chlorine contained in tapwater. Though unlikely, it can also be caused by introducing laundry bleach or pool Chlorine.

Chlorine is a highly reactive substance which causes "burning" in living tissues. Cells are broken down and no longer function properly. At levels considered toxic to aquarium fish, Chlorine isn't appreciably assimilated into the body, but does damage the skin and more importantly, the gills. The gills become incapable of absorbing Oxygen, and the fish develop Hypoxia.

Course Of Action: Move fish to a tank without Chlorine, or perform heavy water changes to remove contamination. Water conditioners containing Sodium Thiosulfate may be added directly to aquarium for emergency situations (not recommended under ordinary circumstances). To prevent Chlorine from entering the tank, add appropriate Chlorine removing products before ading tap water to the aquarium. Alternatively, letting tap water to sit for 48 hours before adding it to the aquarium will allow the Chlorine to disspiate into the atmosphere. An airstone will also help accelerate the process. (NOTE: Most sources state that 24 hours is sufficent time to outgas Chlorine from tap water. The author recommends 48 from personal experience involving certain pond organisms, which invariably died if the water sat for any less time.)


Symptoms: Chloramine can cause the same symptoms as mentioned for both Chlorine and Ammonia.

Cause(s): Adding tapwater that has been treated with Chloramine. Adding Chlorinated water to a tank containing Ammonia.

Chloramine is a compound formed by the union of Chlorine and Ammonia. The molecular bond is fairly strong, and Chloramine can take over a week to disassociate. Once separated, the Chlorine will take 48 hours to outgas, while the Ammonia will spike to levels that the established cycle is not able to handle. From the moment Chloramine is added until its individual components have disappeared, it can cause serious health problems and death.

Course Of Action: Perform large water changes. (up to 90%). Should be repeated for a day or 2. To prevent the addition of Chloramine into the tank, a water conditioning product should be used on any new water. However, never use conditioners that are formulated for the removal of only Chlorine. To do so would disassociate the Chloramine molecule, and cause a rapid spike in Ammonia levels.


Breathing Issues

Hypoxia (Lack Of Oxygen)

Symptoms: Flared gills covers, reddened gills, rapid breathing, gasping at the surface of the water, loss of body color, nervousness and lethargy.

Cause(s): Low dissolved gases in water caused by insufficient aeration, over-crowding, decaying processes of food and other organic matter. Less commonly, an excess of plants or algae may rob the available Oxygen if lighting is insufficient. It should also be noted that many of the toxins or other negative environmental factors mentioned on this page also cause Hypoxia by way of gill damage or interference with other natural body processes.

Course Of Action: A good water change (25-50%) should be performed, and vigorous aeration should be provided immediately. Filters should be cleaned and filtering media should be replaced. Gravel should be vaccumed, and any and all visible decaying matter such as rotten food, dead plants/fish, etc., should be removed from the tank. Water quality values should be checked (pH, Ammonia, Nitrites) since these can contribute to or suffer from the overall problem. Verify that the temperature of the water is in the proper range for you fish. (cooler water holds more gas than warmer water)

Proper aquarium maintenance is the first most important step in avoiding this problem. Along with the proper use of aquarium products such as medecines, and avoiding the introduction of toxic substances, this should virtually eliminate the risk of Hypoxia.

Gas Bubble Disease (Nitrogen Narcosis)

Symptoms: Heavy gasping, loss of balance, fish seem more buoyant though they may not necessarily be floating at the surface. Upon closer inspection, small bubbles may be seen in the fins, and blisters may appear on the body, most commonly around the face and eyes. Bubbles and blisters may perforate the skin, leaving wounds on the body, or red streaks on the fins. Bubbles can also form within the tissues and blood, and can lead to organ damage and death.

Cause(s): Water which is oversaturated with atmospheric gas. The most common cause of this seems to be adding water of a lower temperature to the aquarium. Cooler water naturally holds more gas than warmer water, and when cooler water starts warming up it releases the excess gases. Tapwater, if added immediately after it has been collected, can also sometimes be oversaturated because of the screening on the faucet, which momentarily seperates the water into tiny droplets and allows the incorporation of excess gas. Algal blooms and an overabundance of plants can also over saturate the water if lighting is too bright or constant. Occasionally, a fault in submersed motors (such as those found in filters) can also cause an oversaturation of gases in the water.

A fish located in water that has become over-saturated with gases will only develop Gas Bubble Disease when the water begins to normalize its gas content too quickly. The tank and decor may develop bubbles during this process where current is poor. As the gas levels in the water reduce, the excess Nitrogen previously assimilated by the fish starts to expand, causing bubbles to form.

Course Of Action: Most sources recommend speeding up the release of excess gases in the water by increasing current flow or surface agitation, and turning off the lights to stop any plants or algae from.

Gently place the fish into another tank with more proper oxygen levels. If this is not possible, a 50% or more water change must be performed. Power filters should be turned off and removed from the tank, but free airstones or simple surface agitation help dissipate the excess oxygen into the atmosphere. Remove any charcoal from the filters for a day or 2.

Carbon Monoxide Poisoning

Symptoms: Gasping, darkened gills, confusion, agitation and/or lethargy.

Cause(s): Carbon Monoxide usually enters the tank via the air. Improper heating equipment which use combustable fuel, and badly managed fireplaces are usually the culprits.

Carbon Monoxide is so dangerous because it irrevesably binds itself to Haemoglobin in the bloodstream. This means that the organism can neither accept new Oxygen into the blood, nor release Carbon Dioxide back into the environment. The Oxygen in the blood becomes depleted, and body tissues begin to die. Particularly susceptible is the brain, which can quickly succumb to the lack of Oxygen.

Course Of Action: Note - This problem is as dangerous to humans as it is to fish! The effects are not always apparent right away, and can manifest themselves up to a few hours after exposure.

Carbon Monoxide levels should be checked and source(s) should be located. Carbon Monoxide detectors are a wise safety precaution. Any room or building with Carbon Monoxide present should be well ventilated, and evacuated until the danger has passed. In many localities, emergency medical hotlines, hospitals or clinics can advise you on the necessary procedures and risks for this problem.

Once the area is safe, you can then proceed to save your fish, assuming there are any left to save. A complete and immediate water change is advised. Vigorous agitation should help expel any remaining Carbon Monoxide. Charcoal is of no benefit for this situation.


Excess Carbon Dioxide

Symptoms: Gasping, darkened gills, agitation and/or lethargy.

Cause(s): When one adds CO2 to the tank for plant fertilization, there is a risk of oversaturating the water. This can happen by setting release valves to allow too much CO2 into the tank, or by the equipment itself developping a fault. Other processes can also lead to a build up of CO2. A heavily planted tank left for too long a period in darkness can also increase its CO2 levels. A tank overstalked with fish will also be a risk, though usually other problems present themselves before the CO2 becomes directly dangerous.

CO2 can be dangerous in a number of ways. Besides simply depleting available Oxygen (by taking up valuable space) it can lead to a dangerous slide of pH towards a toxically acid level. Overabundant CO2 can also cause acidosis in the bloodstream of the fish, poisoning them from within.

Course Of Action: Any possible sources of CO2 should be discontinued or eliminated. Check equipment if you use CO2 devices. Vigorous agitation of the water should normalize the amount of CO2 present with the levels of the room the aquarium is located, assuming the air in the room itself is well ventilated and contains normal CO2 levels.

Hydrogen Sulfide (Rotten Egg Smell)

Symptoms: Gasping, darkened gills, increased respiration rate, shimmy.

Cause(s): Sudden shortage of Oxygen in gravel and filters, due to filter stopage or addition of certain chemicals.

Hydrogen Sulfide is created when the beneficial bacteria in a tank die suddenly. This pervades the water, enters the bloodstream of the fish, and combines with iron, rendering the blood cells unable to transport Oxygen and Carbon dioxide.

Course Of Action: If the rotten egg smell is detected, the fish should be removed to a new tank or holding bucket with fresh water. The gravel and filter(s) should be removed and well cleaned. The tank should be refilled with new water. Vigorous aeration will help eliminate any traces of the gas. Fish can be put back when the smell disappears.

To minimize the risk of this problem, clean the filters and vaccum gravel regularly. Should a prolonged power outage occur, check tank often (yes, that means sniff), and remove filter altogether for thorough cleaning.


Introduced Substances


Symptoms: General illness symptoms, falshing, gasping, reddened gills, erratic swimming. Depending on the metal involved, confusion can set in without other symptoms being obvious.

Cause(s): There are many ways metal can enter the aquarium. Water from corroded pipes, improper decorations or equipment, nails, screws, pennies, and even some medications which contain metallic compounds such as Copper Sulfate.

Generally, fish can handle only the smallest trace amounts of certain metals in the water. Metals bind to gills and other tissues, effectively stopping proper functioning. One or more organs can become affected at a time. Iron seems to affect the primarily the gills, lead the nervous system, and copper can affect the whole body, especially the liver.

Course Of Action: A complete water change is recommended. The addition of activated Charcoal may be of some benefit in certain circumstances. Some water conditioners claim to eliminate heavy metals, so adding the proper ammount at every water change should help minimize the risk.

To further guard against introducing metals into the tank, make sure that everything you use in and to do with the aquarium is metal free and in good condition. Plants and rocks from polluted sites may contain metal contaminants. Old equipment may degrade and release metals into the water. For example, cheap nets can develop rust which will be introduced into the water every time you use it.

Garden Hoses and other PVC products

Symptoms: General confusion, erratic swimming, spinning or resting upside down, redness of gills and gasping (not at the surface). Possible secondary bacterial infections.

Cause(s): PVC (Polyvinyl Chloride), the plastic from which garden hoses and many other plastic products are made of, is well known to carry a plethora of toxic elements and chemicals. A small list of known PVC contaminants includes Lead, Cadmium, Chlorine, Dioxin, Phthalates, and Phenols. Fungicides are also often added for obvious reasons. Alone, each substance is dangerous enough, but when combined, they can form even more toxic substances. Garden hoses rank as one of the most dangerous PVC products, due both to fabrication methods, and to the fact that the softer plastic more readily releases its' components into the water. As well, any water left in the hose when not in use will saturate with the chemicals (as well as develop noxious bacteria!).

Be aware that there are a number of different kinds of plastic, PVC being only one. For the modern aquarist, plastics are must, and many products can be safely used, such as decorations, filters, containers and buckets for water changes, etc. A general rule that could be followed is if a plastic can bend easily, and gives off a "plastic" smell, it should not be used.

Course Of Action: Transfer all fish to a tank filled with uncontaminated water, otherwise perform a large water change. Addition/replacement of activated charcoal may be of help. Large daily water changes should be performed for at least a week. Vaccuming the gravel may also be of some small benefit in removing any built up traces of the toxin. Collect and remove as much algae as possible, and remove plants. These may have accumulated the toxins within them which they would eventually leach back out.


Cleaning Products, Sprays, Air Fresheners, Pesticides, etc.

Symptoms: Dependant on product used and amount used. General illness symptoms can be expected. (Flashing, gasping, reddened gills, etc.)

Cause(s): Any number of household products, alone or in combination, can have serious consequences for water quality, and to the fish themselves. As well as being able to enter the water via the air, contaminated objects and unwashed hands can also contribute to this problem. A list of possible elements and chemicals would be too numerous to list here.

Course Of Action: Complete change of water is recommended if fish are suffering greatly. Removal and rinsing of any contaminated objects should also be done. Activated charcoal will also help remove any traces of the chemicals. Water should be changed every day until the fish seem healthy again.

If the contamination is slight, or you are worried about a one time accidental spraying in the room, a more minor water change may be performed. (at least 50% of the water should be changed.) Activated charcoal should be added to the filter.

Soaps And Detergents

Symptoms: Flashing, gasping, reddened gills, "dry" or rough look to the skin, septicemia, cloudy eyes.

Cause(s): Soap or detergents are usually introduced inadvertently as a residue on equipment that has been cleaned with them, or from improperly rinsed hands.

Soaps and detergents break down the slime present on the body of fish, robbing them of its protection. They are also very volatile, and can "burn" the skin and gills. A further effect is that soaps and detergents will reduce/eliminate the surface tension of the water, wreaking havok on the balance of gases in the tank.

Course Of Action: Move the fish to an uncontaminated tank. Otherwise, immediately perform a large water change. This should be repeated the next day. It is recommended to use a paper towel to wipe the higher areas of the tank while the water level is down, to remove any traces that may have lingered there. Similarly, equipment and decorations should also be well rinsed under clean water.

To prevent this, never use soap or detergents on anything that will come into contact with aquarium water. It should be noted that plastics have an unusually good ability to retain substances such as detergents (or grease, or Ammonia, etc). Plastic buckets or containers that have been previously used for cleaning, chemicals, or food should not be used for aquarium purposes.


Dirty Hands, Used Wash Buckets And Containers, Contaminated Equipment, Etc.

Symptoms: Variable

Cause(s): From food stuffs to toxic cleaning products, anything that comes into contact with your aquarium water will affect the system. Many substances have 'staying power', so even rinsed objects or hands can still transfer them to the water.

Course Of Action: Avoid working around the tank too soon if you have been cleaning the house, working on the car, etc. Avoid the use of old buckets or containers. Plastic easily retains grease and chemicals even after several rinses. If aquarium equipment is exposed to hazardous substances, often some soaking and repeated rinses will remove them, but the effectiveness of this approach depends on the nature of the contaminant.


Medication Poisoning

Symptoms: Somewhat variable. Flashing, breathing disorders, discoloration of the gills, septicemia, nervousness or lethargy, lack of appetite or digestive troubles.

Cause(s): Medicinal overdose, treatment period too long, highly volatile medicinal coumpounds, sensitivity of the certain fish to certain medicinal ingredients, medicinal interactions.

Course Of Action: Large water change. Addition of activated charcoal to filter. Daily water changes for at least 3 days.

It must be understood that while medecines are necessary to treat justifiably sick fish, medecines are also rough on the system of the fish, and they are usually detrimental to their environment as well. Beneficial bacteria and plants may die, drastically increasing the biological load of the tank. Observe the tank often for signs of any problems, which should be dealt with quickly.





Symptoms: Flashing, reddened gills, gasping. In excessive circumstances, fish may become excessively agitated, or lethargic as they begin to suffocate.

Cause(s): Cigarettes, cigars, wood fire, etc.

Course Of Action: Perform at least a 25% water change, add activated charcoal, open windows and doors to ventilate the room. Once the air is smoke free, provide vigorous surface agitation of the water. Additional water changes should be performed daily until the fish seem well again.


Paint Fumes

Symptoms: Flashing, gasping, reddened gills, palor, agitation followed by lethargy, cloudy eyes. Symptoms can occur during or up to a couple of weeks after a room has been painted.

Cause(s): Both oil and latex based paints carry harmful solvents such as benzene, styrene, toluene, xylene, and formaldehyde. These substances, known as VOC's (volatile organic copounds), destroy animal cells. They can be acquired through physical contact, breathing, and injestion. They can also be assimilated into the bloodstream, and can remain there and concentrate in the liver for prolonged periods of time. VOC's are also Carcinogenic (cancer-causing) and Neurotoxic (affecting the brain and nervous system) in nature. They can easily accumulate in the aquarium, and fish are much more prone to the serious effects caused by them.

Course Of Action: Complete water change. If fumes are still present, fish should be removed to another room until well after the fumes have dissipated. Activated charcoal should be used to eradicate any possible traces of the chemicals.


Other Issues


Symptoms: Variable. General confusion, erratic swimming or spinning, loss of balance, are often indicative of head injury. Cuts, abrasions, local swelling or indents, and bent or shredded fins may be signs of local or traumatic injuries.

Cause(s): Numerous. Serious head injuries occur most often when frightened fish swim head first into the aquarium glass. Aggressive fish may inflict injuries upon tankmates themselves, but may also chase a fish into the glass or decorations. Improperly placed decorations in or outside the tank may fall and injure fish. Jumping out of the tank can also injure the fish. (Assuming that you rescued him.)

Course Of Action: Seperating the injured fish into a seperate hospital tank is a must, and the fish must be alone in this tank. Most species of fish will take advantage of his weakened condition to harras or even attempt to eat him. An injured fish should not be caught using a net, but rather a clean container, to minimize struggling. Allow the fish to rest without being disturbed. Treat for bacterial infection if it occurs. Only time will be able to tell whether he may recover or not, but keeping him clean and quiet will avoid any extra problems.


Poor Nutrition

Symptoms: Lack of energy, poor coloration, intestinal disturbances or blockage (increased gas production, constipation, pale excrement, etc.), in extreme cases lesions can be produced, usually around the face (Hole-In-The-Head disease), lowered resistance to stress and illness.

Cause(s): Lack of varied foods, over-reliance on single food product, insufficient amount of food (rare), sometimes may be caused by too frequent feeding of certain foods even if diet is otherwise diverse. (Most commonly live foods such as worms.) Weak or less dominant fish sometimes are unable to reach the food, and may be more susceptible than other tank mates.

Course Of Action: Diet should be well-rounded. Offer a variety of dried, frozen and fresh foods. Whether animal or vegetable, live/fresh foods offer more nutrition than any processed food made from them. As a general rule, carnivores should be offered animal based foods supplemented with small amounts of vegetable matter, while herbivorous fish should receive plant based foods supplemented with small amounts of animal food. Any symptoms caused by poor nutrition should improve or disappear within 2 weeks once the diet has been rectified unless the fish's health has become seriously degraded by prolonged improper feeding.

A special mention should be made for green peas, which have a good laxative effect, and can be used to purge intestinal blockages and disorders. They may be offered whole. If the fish refuse to eat them, they can be mashed and added to chopped fish, shrimp, or other appropriate seafood obtainable at the grocery store. A ratio of 1:1 peas/fish, shrimp, etc. should be used, with water added if necessary to help the mixing process. Allow the mixture to freeze overnight, and offer portions at feeding time.

Behavioral Stress

Symptoms: Dependant on the stress factor at work. Bullying by other fish can lead to extreme timidity and hiding. Frightened fish often dart from one area of the tank to another to avoid the dominant fish(es). Behavioral stress can also be caused by neurotic tendancies, such as overly strong drives. For instance, a Cichlid with a cleanliness fetish could work himself almost to death trying to make a spawning pit perfect.

Whatever the cause, all stress factors (including non-behavioral ones) lead to increased susceptability to illnesses.

Cause(s): Improper selection of tank mates, improper decor for certain species, disturbances from beyond the tank (people constantly tapping the tank, sudden yet reoccuring noises, etc.), too bright or too dark lighting levels, even poor weather can cause agitation in many species.

Neurotic behavior is fairly rare, but it does happen. If no other environmental or behavioral cause can be found, and only one fish seems affected, the problem is probably neurotic in nature. Depending on the exact behaviour, sometimes removal of obssession inducing factors can eliminate or reduce the problem. Inbreeding can sometimes be the cause of abnormal behaviour.

Course Of Action: Remove subordinate fish if aggression becomes too severe. Sometimes a strategic decor can minimize problems, such as offering seperate "caves" for each Cichlid. Certain species are simply inappropriate to combine, so research their needs and behaviour before placing them together.

A blind made from cloth or paper placed on the side of the tank will eliminate frights that occur if a fish is overly sensitive to someone approaching the tank from a particular side.

Inappropriate lighting levels can cause anxiety for some fish. Increase or decrease the luminosity as required by elevating the light, or adding floating plants if lighting levels need to be reduced.

All actions in or around the tank should be done calmly and quietly. Repeated harrassment, such as knocking on the glass, should be discouraged.


Stray Voltage

Symptoms: Nervousness, sometimes but not always extreme. General paleness. Lack of appetite. Fish may try to escape water, may be excessively aggressive, agitated, and under extreme circumstances may develop spasms. Head and Lateral Line Erosion may also occur. Severity of the symptoms depends on the voltage and the amount of time the fish have been exposed to the current.

Cause(s): Faulty wiring of aquarium equipment, cracked heaters or submersable pumps or filters, water leak from tank to exposed circuit (such as the wall socket), battery(ies) dropped in tank. Rarely, metals (which can also be found in certain rocks), can create a constant low grade current in the tank.

Course Of Action: If you suspect an electrical fault affecting your fish, your first priority is to protect yourself! DO NOT touch the tank, stand, external equipment, or the water! Turn off the breaker or remove the fuse that supplies electricity to the aquarium and its' surroundings. Be sure to wear insulated shoes. Then you may proceed to unplug the electrical components of your tank and inspect them visually for any damage or defects. Damaged electrical equipment should be thrown out and replaced with new devices. If water is seen or felt anywhere outside the tank, it could be causing an electrical circuit to the tank. Check for and repair any tank leaks immediately, or replace the tank. For those who own an electrical meter, the probes can be inserted into the water to check for current.

If after all your searching, you cannot find the source of the problem, it is highly recommended to call in an electrician to track down the cause. Once the source of the stray voltage is removed, no further treatment is required.


Bacterial Bloom

Symptoms: Gasping, reddened gills, pale color, periodic excitability which can be accompanied by jumping out of the water, spinning. Water may appear cloudy white and smell milky, though this does not always occur.

Cause(s): Overfeeding, overcrowding, extremely poor filtration, aeration, or current, poor tank maintenance by owner, dead spots.

Many different species of bacteria could be responsible for this problem. Their effects are numerous, from changing the water quality to infecting the fish directly. The most notable effect is usally to deplete the water of Oxygen, leading to Hypoxia.

A power outage that lasts too long can destroy the beneficial bacteria residing in the filter and aquarium, and their decomposition can wreak havok to the water quality, and possibly contributing to an increase of harmful pathogenic bacteria in the water.

Course Of Action: Ideally, fish should be transfered immediately to a new tank with fresh water. If this is not possible, a full water change should be performed. All equipment should be removed, scrubbed and rinsed to remove bacteria. Filtration and aeration should be increased.

Dead spots are areas where little or no current exists. This can often be identified by an excess of mulm or detritus. Either a small rearrangement of decor, or a change in location of the filter, can help divert some current to the area.





Flashing - Scratching on decorations, plants, or substrate, usually at the gill area.

Gasping, - Excessively deep inhalations. Gill plates may be flared, and/or gill rakers may appear pink, violet, or red. Often fish are seen gasping air at the surface of the water when there is a problem.

Head and Lateral Line Erosion - Lesions which appear on and around the head and lateral line of the fish.

Lethargy - Loss of energy. Lethargic fish may often be seen literally lying on the bottom of the tank, or floating listlessly at the surface. Any sensory stimulus provokes little response.

Nervousness/Agitation - Rather self-explanatory. Fish seem jittery. They dart often. They may swim non-stop around the tank. They may jump frantically at the surface of the tank. Normally sedate or gentle fish may suddenly become aggressive towards neighbors.

Shimmy - Basically a repeated horizontal wiggle (from side-to-side). Usually accompanied by clamped fins.

Septicemia - Bleeding on the skin or fins caused by small but profuse vascular eruptions(broken veins). Usually appears as red streaks, or pink/red patches.

Spinning - Fish swimming in circles with their bodies curled. They seem confused, and often swim directly into objects. This kind of swimming if often a sign of brain trauma.



Home Page Are Your Fish Really Suffering From Disease? The Worms! A Cheapskates Guide To The Aquarium Hobby
Copyright to author. Email for questions. Comments eagerly invited.
Last Updated: July 31, 2008