One of the most significant management disciplines confronting the rainbowfish keeper is disease prevention and treatment. John Gratzek presented an overview of the diseases of ornamental fishes in 1980. He reported that most aquarist (60%) who discontinue keeping fishes do so because the fishes die. He identified common problems with keeping ornamental fishes and stated that the treatment of diseased fishes is the most common problem.
There are many types of diseases and health problems that fish can suffer for a variety of causes. In captivity, fish frequently exhibit behaviours which may be described as abnormal because they are not known to be a feature of the natural behaviour of the species, or because they appear inappropriate. The causes of such behaviour may vary considerably, from stress due to their housing conditions - or the nature of captivity itself - but some of them are symptoms of specific diseases.
Fish diseases usually occur as a result of adverse interactions between the fish and their environment. In nature, we are less aware of fish disease problems because sick rainbowfishes are quickly removed from the population by predators. In addition, fish are much less crowded in their natural environment than in captivity and they are usually able to seek out the best conditions available.
The natural environment of a rainbowfish is vastly different from that of an aquarium. In captivity, rainbowfishes are maintained at densities that greatly exceed those normally found in nature. When fish that are already over-crowded in the aquarium are further stressed; for example, by low dissolved oxygen, nutritionally inadequate feeds, excessive handling etc., their natural disease defence mechanisms may be weakened and the ability of the fish to protect itself against infectious diseases is reduced.
A variety of parasites and pathogens can and do infect rainbowfishes. Most are naturally present in low numbers but normally do not cause problems. The natural defence mechanisms of rainbowfishes, such as the mucus covering the skin and various components of the immune system, keep these disease-causing agents in check. Fish gradually develop resistance to local strains of parasites and pathogens but may carry Infectious organisms to another aquarium if transferred.
Disease is rarely a simple association between a pathogen and a host fish. Usually other circumstances must be present for active disease to develop in a population. These circumstances are generally grouped under the umbrella term "stress". Stress is one of the primary predisposing factors of disease and mortality in fishkeeping. Therefore, fishkeeping practises directed at limiting stress are likely to be the most effective in preventing disease outbreaks. There are many publications with in depth information on disorders associated with general "stress factors" in fish.
If you want your rainbowfishes to survive and grow, then it is imperative that their aquarium is maintained under conditions conducive to good health. Regardless of how diligent one is, if you keep rainbowfish long enough you will inevitably encounter a disease problem. Fish disease management and treatment, therefore, are a significant part of the fishkeeping hobby.
To begin to understand why disease outbreaks occur, you must first learn about the fish's environment, the stresses placed on the fish by that environment, and the cause, effect, and importance of diseases. For this reason, it is extremely important that you read and understand a practical book on this subject. Several excellent choices are available and they represent one of the best investments in time and money for the serious fishkeeper.
© Copyright Adrian R. Tappin
Created July, 2005.
Updated February, 2007.
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