Fish Health Protocols

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Fish Health Protocols

• Chris MacWilliams, DVM

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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

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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)

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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

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Iodophors Hypochlorites Oxidizers Quaternary ammonium compounds
Brand Name Ovadine Chlorine Bleach (12) Virkon/Peroxigard (7) Roccal, benzalkonium chloride
Bactericidal /
Virucidal / _
Lipophilic virucidal /
Sporicidal / _
Fungicidal /
Effectiveness in presence of organic matter /
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Mechanism of action Iodophors Oxidizes proteins and interferes with metabolic reactions Hypochlorites Free hypochlorous acid attacks sulfur bonds and general structure in microbial enzymes, other proteins Oxidizers O2 release alters protein structure Quat Ammonium Cationic detergents. act against cell wall lipids in bacteria
Usage notes for working solutions (not accurate for concentrate) Safe for skin contact, mild odor, color fades as potency declines, not effective if prepared with seawater Corrosive to skin and metal, strong odor, high risk to fish, volatile, not effective if prepared with seawater Safe for skin contact, mild odor/few volatiles, color fades as potency declines (Virkon), marked drop in efficacy if prepared with seawater Safe for short or occasional skin contact, odorless, some risk to fish, not effective if prepared with seawater
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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

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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

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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

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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

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Managing Egg Fungal Infections

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

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Egg Picking

• Dead eggs are food for fungus
• After shocking eyed eggs observe eggs for
  mortalities

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remove dead eggs promptly
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Early remove affected
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Grape cluster remove clumps
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Beyond treatment discard tray
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Formalin Egg Disinfection

• 1670 ppm for 15 20 minutes
• Static bath till last few weeks till hatch
• Then keep water flow gt11 lpm
• Hanging IV bags or chicken feeders

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Hydrogen peroxide (Perox-Aid)

• 500ppm for 30 35 minutes daily
• Comparatively environmentally benign
• Will not work on established fungal infections
  only preventative

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Others

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

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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

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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

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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

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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.

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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
  

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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.