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Fish Health Protocols

Fish Health Protocols. Chris MacWilliams, DVM. Principles of Disinfection Disinfection: process that reduces or eliminates pathogenic microorganisms. Cleaning is the most important step in the cleaning and disinfection process Cleaning process has 5 steps: Dry clean Wet wash

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Fish Health Protocols

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  1. Fish Health Protocols Chris MacWilliams, DVM

  2. Principles of DisinfectionDisinfection: process that reduces or eliminates pathogenic microorganisms Cleaning is the most important step in the cleaning and disinfection process Cleaning process has 5 steps: Dry clean Wet wash Rinse Dry Inspect

  3. Methods of Disinfection • Physical • Moist heat • UV light • Drying • Exposure to sunlight • Chemical • Chlorines (bleach) • Iodines (Ovadine) • Quaternary ammonium compounds (Diquat, Roccal) • Oxidizing agents (Virkon, Ozone)

  4. Chemical Disinfectants • Considerations: • Proven efficacy against pathogens of interest: • Bacteria, virus, protozoans, fungus, spores • Safety • Fish, user, equipment, environment • Affordable • Other: • Presence of organic matter • Effects on metals/fabrics/rubber

  5. Ovadine Egg Disinfection • Why? • Vertically transmitted diseases • On the surface of the egg • Within an egg • Disinfecting eggs significantly decreases pathogen loads • When? • During water hardening • After egg shocking and picking • After eyed eggs are transferred to a site

  6. Ovadine Egg Disinfection • How? 100 ppm = 10 mls of Ovadine per litre of water • Determine volume of heath tray • Add appropriate amount of Ovadine to tray full of water • Gently pour rinsed, fertilized eggs into tray preloaded with Ovadine solution • After 10 minutes without disturbance, restore water flow

  7. Ovadine Egg Disinfection • 1 volume of eggs : 10 volumes of disinfectant solution • Solution colour indicates efficacy Brown = active Yellow = inactive and should be refreshed • Make a fresh Ovadine solution for each lot of eggs

  8. Ovadine Egg Disinfection • Spent solution disposal • Dilution is standard, combined with hatchery effluent, or can be disposed to ground Neutralize: Sodium thiosulfate 0.78 X grams of iodine x 2 (safety factor) or 0.15 gm per litre of 100ppm solution Water should be colourless before discharge to ground

  9. Managing Egg Fungal Infections • Egg picking • By hand • Mechanical pickers • Chemical treatments • Formalin (Parasite-STM) • Hydrogen Peroxide • Salt • Bronophol (EDR) • Malachite Green

  10. Egg Picking • Dead eggs are food for fungus • After shocking eyed eggs – observe eggs for mortalities

  11. remove dead eggs promptly

  12. Early – remove affected

  13. Grape cluster – remove clumps

  14. Beyond treatment – discard tray

  15. Formalin Egg Disinfection • 1670 ppm for 15 – 20 minutes • Static bath till last few weeks till hatch • Then keep water flow >11 lpm • Hanging IV bags or chicken feeders

  16. Hydrogen peroxide (Perox-Aid) • 500ppm for 30 – 35 minutes daily • Comparatively environmentally benign • Will not work on established fungal infections – only preventative

  17. Others • Salt – Robertson Creek every 2 – 3 days • Bronophol – no benefits vs approved • Malachite Green – absolutely not!

  18. Sample Shipping to a Diagnostic Facility • Mortalities are unexpected • Clinical signs are suggestive of a disease of concern (eg. popeye and/or swollen abdomens at a facility with a history of recurrent BKD infection) • Daily mortality rate exceeds 0.5% of the population

  19. Selecting the samples • Moribund fish preferred • There may be a need to randomly sample apparently healthy fish from the population • Ask Fish Path Lab staff re: sample type, numbers and shipping info

  20. Before shipping • Collect fish history: • population size • clinical signs • mortality and morbidity rate • diet and feed consumption • water quality conditions • records of recent stressful events (e.g. low water event, marking) • vaccination status • disease and treatment history • Fill out a submission form

  21. Shipping Live Fish • Line a cooler with ice paks or double bagged ice • Cover ice with newspaper • Live fish are added to heavy duty plastic bag filled ¼ to 1/3 full of aerated ambient water • Oxygen is pumped into the bag to refill it. • The bag is securely closed off using elastic bands or tape. Double bag and placed in the Styrofoam cooler. • Each bag is clearly marked with information identifying contents. • The remaining space in the cooler is filled with cubed ice to keep the fish and water cool. • The lid is placed on the Styrofoam cooler and securely fastened with duct tape to prevent accidental spillage.

  22. Shipping • Include a pathology laboratory submission form or an accompanying letter with more detail • Include copy of mortality records if available • Clearly mark sample bags • The container is addressed to the laboratory at PBS and is clearly labeled with information as to originating site. • Contact lab with estimated time of sample arrival

  23. Shipping fresh dead fish • Fresh morts (red gills, firm flesh) should be placed in labeled, sealed double plastic bags without water. • Ship dead fish in a container on ice as described above for live fish. • Fish should not come in contact with the ice or freezer packs.

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