Every fish farmer desires to make profits from his or her fish farming business, however, fish diseases can affect the overall performance of the fishes which in return will led to loss for the fish farmer, therefore measures must be taken in identifying and preventing or treating of these diseases in order to prevent these losses. But first, how can you identify these fish diseases?
The following are identified types of diseases based on their causes:
(i) Infectious Diseases: These are caused by germs or pathogens such as bacteria, fungi or viruses. They attack living tissues, live and multiply there and eventually cause death.
(ii) Parasitic Diseases: These are caused by organisms called parasites which live in or on other animals, known as hosts. Fish parasites include protozoan, crustaceans and worms. They derive nourishment from tissue or fluid of their hosts.
(iii) Nutritional Disease: Improper diet such as deficiency or imbalance in the nutrient composition of feeds.
(iv) Environmental Diseases: These are caused by pollutants from various sources including agricultural run-offs, industrial effluents domestic effluents etc..
Prevention of Fish Diseases
A fish farmer should aim at preventing (prophylactic) rather than treating diseases (therapeutic). Good farm management is of primary importance in avoiding disease and parasite attacks. The working principles are:
1. Provision of Good Quality and Pathogen Free Water: Ensure that pond and hatchery water is in sufficient quantity and readily available at all times. Water should not be passed from one pond to another.
2. Control of Wild Fish and Predators: Wild fish live in canals and other natural water bodies. They are therefore potential hosts and vectors for disease pathogens. It is therefore recommended that they should be barred from gaining access into ones farm by:
– Placing wire mesh screens on all water inlets
– Use of chemical on them before stocking the pond
3. Stocking Density: Avoid overcrowding of fish at any time particularly during hot weather. Observe recommended stocking rate for each fish species and for species combination.
4. Broodstock Management: Preventive treatment should be given to broodstock before they are used for spawning. They should be separated from young fish hatchlings as soon as possible.
5. Pond Conditioning: Pathogens and diseases vectors develop in cycles. In most cases their spores, eggs and cysts survive in pond bottoms. Periodic drying and liming of ponds kill the eggs or spores and their intermediate host (e.g. snail and aquatic weeds).
6. Treatment of Fish before Stocking: Fish should be given bath treatment before stocking. Transfer of fish from small to bigger ponds reduces the chance of reproduction in parasites.
Read Also: How Does a Farmer Know His Fish Is Diseased?
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