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Prevention of Fish Disease

Prevention of Fish Disease

a) Importance:

  • It is difficult to identify the appearance of disease in its initial stage on account of the gregarious nature of fish in water which causes difficulties in observation, diagnosis and timely treatment.
  • Apart from this, some effective drugs and measures to cure certain fish diseases are still not known well. Therefore, perfect preventive measures must be taken since this is a key link in fish disease control.

b) General Preventive Measures:

  1. Increasing the internal resistance of fish is important in the prevention of diseases.
  2. Selection of healthy fish seed.
  3. Proper density and rational culture.
  4. Careful management
  5. Qualitatively uniform ration and fresh food.
  6. Good water quality.
  7. Prevention of fish body from injury.

Abolishing Pathogens and Controlling Its Spreading:

  •  Existence of pathogen is one among three factors (Host, Causative Agent and Environment) in outbreak of fish disease.

Controlling Measures

1. Thorough Pond Cleaning and Disinfection

  • Bleaching powder (chlorinated lime) should be applied at the rate of 50 ppm in the pond.
  • It readily kills all the wild fish species, molluscs, tadpoles, crabs and disinfects pond soil and water.
  • In nursery and rearing ponds, it is desirable to use malathion at the rate of 0.25 ppm 4-5 days prior to stocking of fish seeds.

2. Disinfection of Appliances:

  • Nets, gears, plastic wares and hapas should be sun-dried or immersed in a disinfected solution.

3. Disinfection of Fingerlings and Feeding Platform:

  • Disinfection with mild concentration of potassium permanganate solution is helpful during the transfer of the fingerling to stocking tanks.
  • The feeding platform can be disinfected by hanging bleaching powder cloth bags with mixture of copper sulphate and ferrous sulphate (ratio 5:2) near the feeding place.
  • When fish come to the feeding place for feeding purpose, their skin will be automatically disinfected.

4. Proper Feeding:

  • Fixed quality, quantity, time and place have to be followed for proper feeding.
  • Any reduction in quality and quantity and variations in feed application and place may cause not only deficiency disease, but also will increase the susceptibility to many infectious diseases.

5. Segregation of year class fish population:

  • Brood and older fish may serve as carriers of disease causing organisms without exhibiting any clinical symptoms.
  • To avoid such risk, young fish should be segregated from the brood and older fish.

6. Spot removal of dead fish from the pond:

  • Dead and sick fish should be removed as soon as it is located.
  • The daily loss of fish should be recorded to provide valuable insight to the intensity of disease problem.

7. Chemoprophylaxis:

  • Effective and inexpensive prophylactic measures against wide range of parasitic and microbial diseases are advisable as chemoprophylaxis.
  • Occasional pond treatment with potassium permanganate at the rate of 2 -3 ppm and dip treatments with potassium permanganate at the rate of 500 - 1000 ppm for 1-2 minutes or short bath in 2-3% common salt solution is safe.

8. Immunoprophylaxis:

  • Immunisation programme is gradually emerging as one of the most important measures for preventing infectious disease.
  • Vaccine against Aeromonas hydrophila, Plexibacter columnaris, Edwardsiella tarda, E.ictaluri, Aerononas salmonicida, Yoreinia ruckeri, Vibrio angullaram and several viral pathogens such as IPNV (Infectious Pancreatic Necrosis Virus). CCVD (Channel Catfish Virus Disease), VHSV (Viral Haemorrhagic Septicaemia Virus), IHNV (Infectious Haemopoitic Necrosis Virus), etc. are being tried on large scale.
  • Serodiagnostic methods that included Fluorescent Antibody Test (FAT), Enzyme Immuno Assay (EIA) and Passive Haemagglutination (PHA) are employed.



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