All living things in certain circumstances are subject to ill-health and diseases, and fish is no exception. It is possible that at one time or the other the fish farmer has to deal with disease conditions of fish in the pond. To do this properly, it is necessary to know something about fish diseases that are likely to be contracted and how they can be prevented or cured. It is quite possible to keep fish in a state of good health.
Generally most of the fish species that perform well under culture conditions in Nigeria have very great resistance to diseases so long as bad handling, unsuitable food, poor water quality, overcrowding, or other adverse influences do not weaken them. To avoid disease, the first thing that a farmer should bear in mind is to keep fish in a good culture (optimal) condition, so that they can have a good resistance when any infection occurs.
Most infections however can be avoided through good management practices. It is generally known that occurrences of fish disease in fish ponds are quite few compared with occurrences in the natural environment. This makes the management of parasite diseases of fish easier under culture. Conditions that discourage the proliferation of parasites in fish ponds include lack of variety of fish found in ponds relative to natural waters, partial or complete absence of the intermediate hosts of many parasites, and lack of periodic draining and drying of the ponds. Consequently it is parasites with direct life cycles that usually survive in the ponds.
Importance of Healthy Fish Stock
The need for a healthy fish stock in a pond is no less than the need for a healthy living in humans. Every farmer should give priority to the health of fish in ponds for the following reasons.
- For assurance of a profit oriented fish farming enterprise. Fish deaths due to poor health will rob a farmer not only of intended financial profit, but also of the total investment on the farm. This situation can be prevented by proper fish health management practices in the ponds.
- To ensure good growth of fish. Stunted fish (slow growing fish) are often a distaste to most fish farmers and in some instances such experiences have made some farmers pack up fish farming practices. When fish are given balanced and regular diets with natural foods in a good pond environment, good growth will be assured.
- To prevent disease transmission to man. It is known that man can become infested with tapeworm by eating raw or insufficiently cooked fish. Also a farmer can contact diseases on the skin by gaining access to an infested pond.
Factors Promoting ill Health and Diseases in Cultured Fish
Factors that promote ill health in cultured fish or favor occurrences of fish diseases are mainly management/environmentally based. When a fish farmer is careful in preventing the occurrences of such conditions, fish culture will be a pleasant experience with the expected benefits. Such factors include:
- Poor Water Quality
- Erratic (Irregular) Feeding
- Nutrients Deficient Feeds
- Over fertilization
- Incidence of Predators and Wild Fish
- Bushy and Unhygienic Pond Environment
Raising healthy fish is possible and it is a key to profitability and sustainability in fish farming business.
Nicholas Izekor is an Aquaculture Trainer at The Ark Shore Konsults (T.A.S.K.). He holds a Bachelor’s degree in Fisheries Management from the University of Benin, Nigeria.