In certain circumstances diseases can affect all living creatures, and tropical fishes are no exception. First of all be watchful when buying fishes, get them from a reputable dealer, and make sure they are disease free. They should be alert, active, and have erect fins. An invaluable piece of equipment is an extra tank set aside for quarantine purposes; this should be set-up with a simple bubble-up sponge filter, a heater, and some suitable shelter. This can be used as a hospital tank, or a quarantine tank for new stock. New stock should be housed for about two weeks in the quarantine tank prior to introducing them into the main aquarium; this will go a long way to ensuring that you have a disease free environment for your fishes.
In general fishes are quite resistant to disease, provided there are no unfavourable conditions present that may weaken their resistance. By far the majority of disease outbreaks are due to poor water conditions, which may directly poison the fishes, or indirectly make them susceptible to diseases. Poor water conditions may include any are all of the following:
> Poisons in the water: i.e. ammonia and nitrites.
> Metals such as lead, copper, or zinc for example, are extremely toxic.
> Insecticides are particularly harmful, low concentrations in the water often proving fatal, refrain from using aerosols in the same room as fishes are housed.
> Temperature changes: These should be adapted to slowly, 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”.
> A sudden rise in temperature may cause respiration difficulties, where gasping and surface hugging may be observed.
> Sudden changes to pH or water hardness can cause stress to your fishes, leaving them vulnerable to disease.
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.
Fishes will show characteristic signs of distress if oxygen levels fall below that which is required by them. Often they can be seen gasping close to the surface in an attempt to take in gulps of air. Although Labyrinths(Anabantoids), and certain Catfishes will do this anyway, because they have the ability to breath air from the atmosphere. Fast swimming fishes may dart about more rapidly.
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.
A common mistake made by novice fishkeepers is overfeeding. Fish do not need as much food as one may imagine, as a result far too much food goes into the aquarium where it sinks to the bottom and starts to rot. Extra food that is consumed by the fishes also falls to the bottom as excrement, where this too starts to rot, the result is an ideal nutrient for the organisms that promote diseases. This concoction also contributes towards the build up of poisonous substances that fish cannot tolerate. Prevention is better than cure, and is achieved by proper maintenance and good aquarium housekeeping.
In the wild practically all fishes are suffering from some sort of ailment, but only mildly, and in the large bodies of water that these fishes inhabit these ailments rarely cause a problem. Conversely, in the aquarium where a much smaller volume of water is contained, the chances of a fish picking up a parasite is greatly increased, any disease getting a foothold in the confines of an aquarium could have a quick and devastating effect. However, if this occurs and your aquarium and water conditions are in tiptop shape the fish will have the resistance to ward of the attack, which will make it difficult for any disease to spread.
There are three main possibilities to the cause of ill health; if any of these are spotted early it could be a clue to the problem:
1. If only a small number are affected this could suggest a non-infectious disease or a malformation.
2. If a small number are affected initially, but then this number increases, then this shows the signs of an infectious disease.
3. If all of the fishes in the aquarium are affected at once, and occurs rapidly, then this points to it being a water quality problem.
Being a fishkeeper and knowing the normal behaviour pattern of your fishes gives you the ideal opportunity to recognise any unusual or abnormal behaviour that they may display. Indicators of poor health may include any of the following:
> Gasping at the surface
> Rubbing against objects
> Becoming darker or lighter in colour (Although this could be due to stress, being startled for example)
> Listless behaviour
> Emaciated appearance.
Other causes could be determined from a closer examination of the fish.
> Look for signs of parasites; they could easily exist in the aquarium.
> When feeding live food: Only Good Quality live food should be offered. Live food that is fed to your fishes should be bought, or cultured if you know how too. Live food that has been caught from the wild, a garden pond for instance, could introduce diseases into the aquarium. The danger of disease being introduced this way is also increased because of the warmer water of the tropical aquarium.
Among the ectoparasites that can be introduced to an otherwise healthy aquarium are Ichthyophthirius multifiliis (Whitespot disease), Hydra (freshwater polyps), fish lice, and leeches to name but a few.
Good aquarium hygiene, and only the best water quality, is the main key to successful fish keeping. It is usually possible to correctly identify why a fish is unhealthy. By using a step-by-step approach, and considering all of the possibilities, you can achieve a result, and the correct treatment can then be administered.
Don’t jump to conclusions, it must be decided first of all why the fish is behaving the way that it is, and the reason for it doing so. Compare it with the things that have been listed earlier, and try to draw a conclusion from it. Many beginners’ start out in the hobby with good intention, only to give up because their fishes become ill or die for no apparent reason. It is also possible that plants could be affected, and to a beginner this gets too much, and he / she loses all confidence, and has no enthusiasm to try again.