Fish health management is important in fish farming business, because pond fishes are always vulnerable to diseases which can harm and kill them due to number of reasons. Disease problem is a substantial cause of economic losses in fish farming. Outbreak of diseases are caused mainly by stress, environmental factors, and also by disease causing organisms called pathogens.
Commercial fish producers as well as recreational pond owners are constantly faced with the challenge of managing fish health. Fish health management refers to management practices which are designed to prevent fish diseases an hence the result loss (death) that follows.
Successful fish health management begins with prevention of disease rather than cure. Once fish get sick it can be very difficult to rescue them.
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Causes of Fish Disease
In nature, a delicate balance exists among the fish (host), pathogens and the environment. A disease breaks out when this delicate balance is upset, exposing the fish to highly infectious pathogen under unfavorable environmental circumstances.
Unfavourable environmental conditions, also referred to as stressors, cause stress to the fish and hence, weaken its defense against diseases.
1. Inadequate nutrition
2. Poor water quality.
3. Rough handling of fish by farm workers
4. Excessive crowding in ponds, and other stressors often contribute to the outbreak of disease in fish farms.
Types of Fish Disease
There are two broad categories of fish diseases that attacks fish ponds, they are, infectious and noninfectious diseases.
Infectious diseases are caused by disease causing organisms present in the pond environment or carried by an infected fish.
They are contagious diseases, and can be controlled by administering some treatment. Example of infectious diseases are fungal, parasitic, viral and bacterial diseases.
In contrast, non-infectious diseases are caused by environmental problems, malnutrition, or genetic anomalies. They are not contagious and usually are not cured by medications. Instead, these problems are often corrected by changing pond management practices.
Symptoms of fish diseases
Observe daily fish behavior and feeding activity for early detection of problems when they do occur so that a diagnosis can be made before the majority of the population becomes sick.
Fish diseases can be observed through changes in their behaviour, appearance, or in the worst case, death. Through careful observation you can confirm if there is a potential disease or parasite in your fish pond.
Endeavour to put yourself and your farm workers through fish health management classes in order to be able to look out for disease symptoms in the fish and avert undesirable end results that may follow.
Also, a frequent look out for symptoms in the fish will greatly reduce management problems and also reduce economic losses in your fish farm.
Some notable symptoms of fish diseases include:
1. Retarded growth
2. Fish jumping out of the water.
3. Parasites on the scales/skin of the fish.
4. Many fish at the surface of water gulping air.
5. Erosion of fins, peeling skin, ulcers and also lesions or cuttings on fish skin.
6. Individual fish swimming unsteadily or randomly.
7. Fish swimming in circles is also a symtop.
8. Unusual colouration of fish skin.
9. Fish try to scrap their bodies on hard surfaces.
10. Swollen fish stomach is also a symptom.
11. Fish flipping on water surface
12. Parasites may become visible on the fins, body, and also on gills of the affected fish.
13. Excess mucus may appear on the skin of the fish.
14. There may be cotton-like growths (fungus) on the skin surfaces.
15. A fish swimming apart from the rest.
16. Loss of appetite by fish.
17. Fish deaths increasing over time.
18. Large number of fish crowding around an inlet of freshwater.
19. Parasitic worms in the internal organs.
When these symptoms are observed, the fish should be evaluated for parasitic or bacterial infections.
Fish Health Management/Prevention of Fish Diseases
The best way to avoid diseases is to prevent them from happening. Most importantly, maintain good hygiene on the farm and also for anything entering the farm.
For effective prevention of diseases, the following should be taken into consideration:
1. Maintain good personal hygiene in the farm: keep hand and foot baths for farm workers and also for visitors.
2. If you have one pond affected by a disease, disinfect any tool used there before using it in any other pond.
3. In order to reduce mortality, reduce or stop feeding the fish. If you can afford it, construct new fish ponds as your fish farming business expands.
4. In addition, reduce stocking density to reduce stress in the fish.
5. Remove dead fish immediately and also any fish showing symptoms of disease.
6. Treat the disease with antibiotics or salt, if prescribed.
7. In severe situations, invite an expert to assess the farm for proper diagnosis
8. In case of serious infection (mass mortality), harvest all and sell immediately, drain your pond, clean and disinfect thoroughly and start afresh.
In case of emergency, use only recommended and approved chemicals and drugs. Target the organisms that are the causative agents of disease occurrence and wipe them out before it gets out of hand.
You should however, use these chemicals in controlled measures. Too much of it will remain in the system of the fish when they are sold to the market.