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Fish Diseases: A Simple Introduction

 Fish diseases affect the survival and growth rates of fish under culture. Given that treatments are expensive, fish diseases invariably lead to lower harvest and higher cost. Fish farmers often suffer hefty economic losses due to fish diseases.

To alleviate such losses, it is crucial to take precautions to prevent fish diseases and reduce pathogen levels in water bodies. It is also important to prevent water quality from deteriorating and to strengthen the natural resistance of the fish stock.

Regular monitoring of fish health is an effective way to identify disease causes and appropriate treatments. One major cause of serious fish kill is overlooking the contagiousness of fish diseases and thus delaying treatment. As such, adequate care and treatment should be given to infected fish promptly.

Causes of Fish Diseases

There are three major causes of fish diseases:

a.       Presence of environmental pathogens

b.      Low resistance of the fish stock

c.       Unsatisfactory water environment

Pathogens (e.g. bacteria, viruses, fungi and parasites) exist in all natural water bodies, yet healthy fish have adequate resistance against them. They can also adapt to reasonable environmental changes and in turn avoid diseases due to pathogenic infection.

When the pathogen level of a water body rises sharply due to external factors, and the natural resistance of the fish stock cannot cope with the increased pathogens, the fish will become vulnerable to pathogenic infection and diseases.

In addition, external factors may also cause drastic changes in water quality, resulting in poor health and low resistance of fish stock. The risks of pathogenic infection and fish diseases or deaths are heightened.

Author Bio:

John Chiseba Mwamba

Fish Farming Consultant at Innovative Farmers and Aquaculture Consultants Zambia Limited.

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