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Diseases in Tropical Fish

Aquarium Illness Facts and Aquarium Care

(The First Tank Guide)

When keeping any animal in captivity, the health and well-being of the animal becomes the responsibility of the owner. When an animal becomes sick, it can be difficult to diagnose the problem accurately, as many of the procedures used in modern medicine are not available for animals, or are prohibitively expensive - and because the fish obviously cannot tell you what the problem is or what is bothering them. However, there are things that a fish owner can do to prevent disease and to keep his pet fish healthy.

Where Do Fish Diseases Come From?

Most disease organisms that can affect your pet fish are already present in all but the newest aquariums. The majority of these bacteria, fungi, protists, and other microscopic parasites (called pathogens) can travel by air for great distances. Some can even survive long droughts, so a long-dry, used aquarium may not be free of disease organisms! So, to all practical purposes, the majority of these pathogens are ubiquitous.

If these pathogens are in everybody's aquariums all the time, you might ask, then, why aren't everybody's fish always sick? People's fish aren't always sick because most healthy fish can fight off the common pathogens with their immune system. The biggest factor in keeping your aquarium disease-free is to keep the fish healthy.

How Can I Keep My Fish from Getting Sick in the First Place?

To keep your fish healthy, your best bet is to keep them in a healthy, low stress environment. More than 80% of disease outbreaks in an aquarium can be traced to failure on one or more of these issues. To keep your tank healthy:

Remember, a stressed fish has a repressed immune system, and a fish with a repressed immune system will not be as able to resist a disease as a healthy fish.

What Can Increase Risk of Disease in My Fish?

In addition, there are some things that will increase your fish's risk of disease. Once a fish becomes sick, the population of disease organisms in the tank increases, and the health of the pathogens also increases. This makes it harder for other fish to resist the disease. For this reason, it is important to remove any sick fish to a hospital tank as soon as you can see signs of ill health.

At this point, it is a good idea to see if you can figure out what caused your fish to become susceptible. Check the points above for some ideas.

Also, if a fish dies in your tank, it is important to remove the body immediately. Not only is the body of the deceased fish contributing to poor water quality by decaying in the tank, but a fish's chance of contracting a disease is many times higher if it eats a fish that was already infected - or worse yet, one that died from the disease!

Water from unknown sources can also be dangerous. Any water from another tank is a potential risk to your fish. When you add water from someone else's tank, you do not really know what pathogens are available in the water and in what population. You do not know if the fish in the tank were about to come down with something or had just gotten over something.

Possibly the worst foreign water is water from a pet store aquarium. Pet stores are getting fish in all the time, and selling those fish (hopefully) quickly. This means that a pet shop may get some fish in with some atypical disease, and sell them all before seeing symptoms. Never let the water from a pet store fish tank into your home aquarium.

Any of these conditions can contribute to an increased pathogen population which could overwhelm your fish's immune system.

Remember to keep a close eye on your fish. Most diseases are much easier to treat if you catch them in the early stages. Should your fish become sick, there are many medications on the market that will quickly and accurately treat most of the diseases your fish are likely to encounter.

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