Aquarium Bible

Signs of Sick Fish

Signs of Sick Fish
Before going on to describe specific diseases its worthwhile looking at some of the signs that may indicate ill health in a fish. Some symptoms depend on the underlying cause of the problem, but in general there are a number of guidelines that would indicate the state of a fish's health.

When a fish is in good health the signs are quite obvious, it will be clean looking, have erect fins, clear eyes, and have good colour. The skin will not show any blemishes and the fins will be not be torn. They will be alert and should dart away at sudden movement near the tank.

If a fish is unhealthy the picture will be recognisably different and any or all of the above features may be apparent. If the fish shows a slimy appearance and rubs against objects in the aquarium then a skin infection could be a possible cause. A fish with obvious signs of breathing difficulties accompanied with pale looking gills is a sign of ill health. An obvious indication that something is wrong is the appearance of abdominal swellings or cysts. But above all I think the best indicator is when a fishkeeper that is well used to observing the behaviour of his / her fishes notices unusual behaviour patterns. Normally active fishes suddenly starting to behave in a sluggish manner for prolonged periods is an indication that something may be wrong.

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Ill health due to environment.

The environment that you provide for your fishes is extremely important and is often overlooked, this results in unfavourable conditions, which cause the fishes to suffer, and is often mistaken for an outbreak of disease.

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Lack of oxygen: (Hypoxia)

Fishes will show characteristic signs of distress if oxygen levels fall below that which is required by them. Fast swimming fishes may dart about more rapidly, they will have increased respiration, fishes can be seen gasping close to the surface in an attempt to take in gulps of air, their gills will open, fishes loose colour, and without remedial action they will die, they will literally suffocate. It is sad to say that this is quite a common cause of death in the aquarium world. Even a temporary drop in oxygen levels will cause stress to fishes which in turn will weaken their defences against disease. Lack of oxygen can arise from several causes, such as overcrowding of the aquarium, rise in temperature, or decaying organic matter, i.e. dead plants, or rotting food. It must also be remembered that the nocturnal respiration of plants will deplete oxygen levels to a degree.

The quickest way to remedy oxygen shortage in the aquarium is by carrying out a partial water change, ensuring that you remove any decomposing material from the aquarium floor. The important thing to remember if you want to avoid the situation arising again, or indeed in the first place, is to clean the aquarium and carry out partial water changes on a regular basis, keep your filters clear from clogging, do not have the temperature higher than is needed for the species that you are keeping (less oxygen is dissolved in water at higher temperatures), and have sufficient aeration via the filter's venturi or a separate air driven device.

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Too much oxygen (Gas bubble disease).

The characteristic sign of this condition in fishes are blisters, or small bubbles that form inside the body cavities, beneath the skin, in the head, and in particular in and around the eyes, causing exophthalmia (an abnormal protrusion of the eyeball or eyeballs). Small bubbles can also form within the vascular system, thus blocking the flow of blood and causing tissue death. A worse scenario is when bubbles form in the gill lamellae and block blood flow, resulting in death by asphyxiation.

'Gas bubble' disease (which is uncommon) is the result of excess gases being dissolved within the fish and its liquid environment, a condition known as “over saturation”, it is not, as one might think, the result of bubbles from the water getting into the fish. Stirring up bubbles during a water change doesn't hurt your fish, although it may hasten the “degassing” a bit.

The principal gases found in aquarium water are Nitrogen (N2), Oxygen (O2), and Carbon Dioxide (CO2). The quantity of gas that will remain in solution in liquid, whether it is water or blood, is governed mainly by pressure and temperature, and at any given temperature there is a maximum amount of gas that a liquid can naturally hold, if this level is exceeded over saturation occurs. Therefore, dissolved gas in the tissue of the fish must be in balance with the water surrounding it.

When this relationship is out of balance (over saturation) the over saturated liquid will constantly attempt to release the excess gas in the form of small bubbles. In simple terms, the fish’s blood is releasing small bubbles to rid itself of excess gas, and it is this that causes what is termed as gas bubble disease. This is similar to when a diver surfaces to quickly from some depth and encounters the “bends”. Problems can arise at 105% saturation, and at 140% saturation and higher gas bubble disease can kill fishes.

As I’ve already mentioned this disease is not commonplace, however the most likely cause if it should occur in the aquarium would probably be due to heavy plant and algal growth combined with excess sunlight. It is probably more likely to occur in lesser tropical situations because cold water actually carries more dissolved gases than warmer waters.

It is obviously better to avoid a situation than to have to cure one, and because equipment for measuring these types of situation are very expensive good aquarium maintenance should be practised, and if excessive sunlight and too heavy a plant growth are avoided, together with good aeration, over saturation can be prevented.

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Fluctuating pH (Acidosis & Alkalosis)

Generally speaking most tropical fishes are happy in a pH range between 6.0 (acidic) and 8.0 (alkaline), there are individual species that have their own sensitivity ranges. The term pH refers to the “power of hydrogen”, and it is measured on a logarithmic scale of 0.0 to 14.0, neutral being 7.0.

It is necessary to maintain a stable pH, and in the correct range, to keep tropical fish healthy and colourful. Excessively acid or alkaline conditions in the aquarium, as well as pH fluctuations should be avoided, it will cause stress to your fishes, and a stressful environment leads to lower resistance to disease, poor fish colour and poor appetite. Any changes made to the pH of aquarium water should be conducted slowly over a number of days to avoid stressing your fishes.

In general, if pH is too low for a particular species, injury to the gills could be caused, along with excess mucus production and skin problems (acidosis), respiration will increase and the fish will be seen gasping at the surface, it may even try to jump out as it darts about, another indication of extremes of pH.

Too high a pH for a species could result in similar symptoms and only a pH check will confirm which. A pH above 9.0 will be accompanied by skin damage, bleeding gills (alkalosis), it can also be associated with ammonia poisoning since higher pH levels can increase free ammonia levels in the water.

Either of these conditions can cause death, an immediate water change is the only remedy. The best thing is of course to avoid the situation in the first place by doing regular pH checks of your aquarium water, at the very least once a week. Be sure that the pH values are correct for the species that are in the aquarium.

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Faulty nutrition

It is a fact that a poor balanced diet will be responsible for the fish’s inability to fight off diseases. If a fish is to live a healthy life it must have a well balanced diet.

An incorrect diet can give rise to various problems, not all of which are immediately evident. Over indulgence of one type of food can lead to intestine inflammation, which will cause loss of appetite, the excreta may be flecked with blood. If this occurs feeding must be stopped for a few days, after which a different type of food should be given. To much fat and carbohydrate can lead to fatty deposits in the tissues, and degeneration of internal organs such as the liver. This won’t be obvious until death has occurred, but can be avoided by a properly adjusted diet.

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Temperature shock

Temperature extremes that go unnoticed for prolonged periods, or sudden changes to temperature are factors that are damaging to a fish’s health. Care should be taken when transferring fishes from one place to another. Temperatures should be adapted to slowly and regular checks should be made to ensure it is within normal limits.

Sudden lowering of the temperature may cause shock, and as a result affected fishes may develop a slow weaving motion, a condition known as “shimmies”, they may remain motionless on the bottom, and they will be susceptible to disease.

Exposure to higher temperatures than normal will cause respiration difficulties, fishes can be seen gasping at the surface, they will dart around the tank and try to jump out. Immediate remedial action is required in all cases, bringing the temperature back within normal limits as soon as possible but not too suddenly.

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Poisons & Toxins

The fishes in your aquarium are extremely susceptible to any changes to its water condition, this leaves them very exposed and vulnerable to any toxic agents that may become soluble in the water. Simple things that you take for granted in your daily life for instance can put your fishes at risk; some of the things that can have an effect on the water in your aquarium are:

> Air fresheners (aerosol)

> Insecticides (fly sprays for instance)

> Furniture polish (aerosol)

> Tobacco smoke

> Freshly painted rooms

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Detergents should always be kept well away from the aquarium, never clean the aquarium or any of its equipment with detergent, this will prove fatal to fishes. Whenever you put your hands into the aquarium water they should be scrupulously clean and free from soap, detergent, or anything else you may have had your hands into prior to working in the aquarium, after washing them run them under fresh water for a few minutes.

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Metals. There are many metals and compounds that you should be aware of that can have a severely toxic effect on your fishes, in many cases low concentrations of them can prove fatal:

> Copper

> Zinc

> Lead

> Cadmium or Nickel from electroplate

> Iron

All of these tend to break down the mucus coating on the skin and destroy the epithelium of the gills causing respiratory problems, and ultimately death. Therefore it is wise not to introduce any metals into the aquarium.

1. Cloudy eyes or skin

2. Blood patches on the fins or skin

3. Listlessness

all suggest metallic poisoning.

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Plastics unsuitable for the aquarium should also be considered, generally plastics with a noticeable smell should not be used, better still only use products specifically for aquarium use.

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Chlorine is extremely toxic to fishes and can prove fatal, it causes gill damage; it is easy to remove from tap water by adding a proprietary chlorine remover (dechlorinator).
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