Fish & Invertebrate Preventative Medicine Flashcards
1
Q
Describe the general rule of fish acquisition and transport.
What are the goals of transport?
What are the main steps of transport?
What considerations for sustainability need to be made?
What water quality issues occur with transport? How can these be minimized?
A
- Introduction
- Core principles
- Maintain DO2, pH and temperature
- Reduce NH3 buildup
- Avoid abrupt changes to water chemistry
- Reduce risk of trauma
- 4 main steps
- Pre-transport planning
- Transport
- Acclimation on arrival
- Post-transport review
- Core principles
- Source and sustainability
- Review natural history to ensure that needs can be met throughout lifetime
- Evaluate source for sustainability, fish health,
- Routinely assess transport and quarantine success rates
- Cultured or previously wild-caught fish
- Often adjust well to new environments
- Vendors, aquaculture facilities, government hatcheries, research facilities, private collections, zoos, aquariums
- Recently caught wild fish
- Available from vendors, wildlife collectors
- Permits generally needed to remove from wild
- More likely to carry variety of pathogens, more difficult for fish to adjust
- General principles of acquisition and transport
- Catching fish risk trauma, exertional myopathy
- In closed transport system, O2 can deplete, NH3 buildup is toxic, CO2 lowers water pH
- Reduced pH slightly protective against NH3 as more shifts to NH4
- CO2 released when container opened and can rapidly increase pH, risking NH3 toxicity
- General principles
- Reduce risk of trauma
- Soft nets, short capture/transport time, recovery time after transport, stretcher training
- Maintain appropriate DO2
- Closed systems with added O2
- Reduce NH3 buildup
- Pre-transport fasting, short transport time, low density, large volume, NH3-locking compounds
- Maintain appropriate pH and manage CO2 buildup
- Adequate buffer, off-gassing during long transports
- Reduce temp fluctuations
- Careful timing, insulation, climate control, short transport time, acclimation
- Minimize water chemistry changes
- Match source and destination water chemistry, acclimation
- Reduce risk of trauma
2
Q
Describe the risk assessment that goes into planning fish transports.
What physical factors need to be considered?
What factors about the fish species need to be considered?
What preshipment conditioning can be performed?
How should fish be fed and fasted prior to transport?
A
- Preparation
- Risk assessment
- Physical factors
- Distance and transport time – risk increases with transport time
- Complexity of transport – minimize number of parties
- Differences in source/destination – compare water temp/chemistry
- Volume of transport water – larger volume is lower risk but higher cost
- Pelagic species need enough water to allow normal swimming
- Water quality management
- Water changes, buffers, NH3-locking compounds may be needed
- Perform testing on arrival
- Experience – seek out experienced people for advice to manage acquisition
- Holidays – avoid during transport
- Weather – avoid extreme weather
- Animal factors
- Species and life stages
- Fine-scaled fish, fast-swimming or pelagic fish, ram-ventilating elasmobranchs, and small fry have highest risk
- Animal size – larger specimens more tolerant of environmental changes, but more prone to trauma
- O2 requirements
- Fish consume more O2 during transport
- Ram-ventilating elasmobranchs, pelagic fish have high O2 needs
- Health state
- Recent morbidity/mortality or those in thin body condition are poor candidates
- Physiologic state – recent stressors present risk, short rest before transport
- Species and life stages
- Physical factors
- Pre-shipment conditioning
- Housing in suitable, isolated system
- Approximate changes in water chemistry to approximate destination water
- Allow recovery post-stress
- Conditioning large elasmos to smaller glide paths
- Mock transports
- For large, high-risk fish
- Can transport small group in aquaculture before putting entire group at risk
- Feeding and fasting
- Fasting fish prior reduces NH3 buildup but can deplete glycogen stores
- Use of immune stimulants becoming more common
- Vitamin C 2000mg/kg PO
- Risk assessment
3
Q
Describe the transport of fish.
What containers are available?
What additives are commonly added to the water?
What type of monitoring can be provided?
What transport options can be used?
A
- Transport containers
- Shipping bags
- Sealed shipping bags in insulated container most common
- Use water from current system
- 1/3 water to 2/3 air or oxygen
- Rigid transport containers
- For fish that will puncture bags, larger specimens
- Open-topped useful in some situations
- Allow off-gassing, visual monitoring
- Lids prevent spillage, fish jumping out
- Can add air pumps, viewing windows
- Additives
- Buffers (NaHCO3, Na2CO3, tris) – important with large sharks
- Ammonia-locking compounds (Amquel, zeolite, nitrifying bacteria)
- Low salinity for freshwater species (0.5-3g/L) – reduced osmotic stress, reduce impact of nitrate buildup
- Low dose of anesthetics to reduce stress – excessive depth, hypoventilation are risks
- Temperature control
- Match target water temp
- Good insulation, heat or ice packs
- Filtration and monitoring systems
- DO2 meters, filtration, staged transports, water quality monitoring at end of transport
- Staffing and medical intervention
- Number of people depends on type and length or transport and the species
- Shipping bags
- Transport options
- Road – trucks with larger transport containers
- Air – delays more likely
- Boat – impractical for large shipments, can do frequent water changes
- Parcel carrier – pre-approved as live fish shipper
4
Q
Describe the acclimation of new fish.
A
- Acclimation on arrival
- Gradual water changes to allow fish to adapt to water chemistry and temp
- Expect if transport carrier was drained, water obviously fouled, significant morbidity occurred
- Float transport bag in destination water and slowly add new water over 20-60min
- Drip acclimation
- Howdys may be needed if introducing fish to one another
5
Q
Describe the legislation governing the movement of fish.
What fish species are CITES protected?
A
- Legislation
- CITES protected – arowana, arapaima, sturgeon, seahorses, humphead wrasse, totoaba, some elasmos
- International air transport association liver animal regulations – for animals on flights
- Magnuson-Stevens Act governs marine fisheries in US federal waters, transport restrictions
- USDA health certificates
- US Department of Transportation has shipping regulations
6
Q
What is the primary goal of quarantine?
What are teh six core concepts with fish quarantine?
A
Clin Fish Med Ch A15 - Fish Quarantine
Intro
- The primary goal of fish quarantine is to reduce the risk of introducing significant pathogens into an established collection.
- Fish are susceptible to a wide range of opportunistic pathogens that are common in the environment and on other animals.
- Quarantine also allows fish to recover from transport and adapt to new environments and diets.
- There are six core concepts with all fish quarantine: acquisition planning, appropriate isolation, ideal environmental conditions, monitoring, reactive diagnostics and treatments, and accurate records
- A well-managed quarantine can significantly reduce the risk of a serious disease outbreak and the loss of established animals.
- It is important to have measurable quarantine goals.
- High mortalities should never be considered an inherent part of fish quarantine
7
Q
Describe the planning that needs to go into fish acquisition?
What husbandry reviews need to be accomplished prior to acquisition?
What considerations about quarantine space need to be made?
A
Acquisition planning
- If a fish species is new to a collection, the natural history and recommended husbandry care should be reviewed.
- Sourcing of the animals should be considered before collection plans are put together and prior to each acquisition.
- Every effort should be made to acquire fish only from reliable institutions or sustainable wild sources.
- Good transport planning is also important, since transport is a significant stressor
- Acquisition planning must consider the available quarantine space
- Animals should only be added to systems that have established biological filters.
- All-in-all-out practices are an excellent way to minimize disease transmission; in these, a quarantine system is used for a single group, then remains empty until the next group arrives
- Recommend a max of 7 days for adding new fish to the quarantine system once started
8
Q
How should quarantine systems be isolated?
What biosecurity measures should be in place?
How long is it recommended that fish be isolated before introduction?
A
Isolation
- At best, isolation means independent quarantine systems that are in a different location from the systems that house the collection
- Each quarantine system should be isolated from any other quarantine system in case of a disease outbreak in one.
- This requires separate equipment for each system, suitable personal protective equipment (e.g. gloves) and hand-washing areas, and adequate space between the systems
- Within a quarantine system, it is often useful to have more than one tank to allow fish to be separated from the group
- The Association of Zoos and Aquariums (AZA) recommends at least 30 days of isolation–some species/systems may require longer
- Mechanical filtration and disinfection of incoming water is recommended where surface water is used or where water is coming from other systems holding animals
- Disinfection of the recirculating water should also be considered (UV or ozone)
9
Q
Describe the ideal environmental conditions for fish in quarantine.
What types of food are recommended for fish acclimating?
A
Environmental Conditions
- Important to have ideal environmental conditions even though it is temporary
- Stocking density important
- Temperature, water quality, should all be appropriate
- Can be difficult due to variance of bioloads and cycling
- Social needs of the animals should be met–separation if aggression occurs
- Suitable substrate
- Fish in quarantine are often transitioning onto new diets. This is particularly challenging with some wildcaught fish
- A wide variety of food items should be available in order to help transition the fish.
- Acquiring these for immediate use is not ideal; it is much safer to use live foods that are from a stable, healthy population
General Planning
- Facilities
- Isolation
- Low traffic area
- Avoid cross contamination (tanks with lids)
- Designated equipment
- Smaller systems easier to maintain to less affected if there is problem
- Disposable filter material (sponges)
- No or minimal substrate
- Absorptive filters to remove medications
- In between quarantine- maintain healthy bacterial population in water
- Redundancy in life support.
- Minimal quarantine is 30 days- 60 days for wild caught animals, 90 days for animals not treated for protozoal ectoparasites
- Be sure to have proper foods available
- May need live foods initially for wild caught sp.
Prior to Acquisition
- Animals provisionally allocated to systems based on environmental requirements, compatibilities and target stocking density
- Take into account species sensitivities to certain treatments
- Have available tanks in case populations or individuals need to be separated
- Water quality should be in target range prior to arrival, established bacterial loads
10
Q
What monitoring should be performed on fish undergoing quarantine?
What clinical signs in quarantine fish suggest an exam is warranted?
A
Close monitoring
- Close monitoring is key to quarantine success
- Water quality monitoring is essential
- Regular visual exams are important (recommend BID at least)–large fiberglass windows are helpful
- Clinical signs that warrant investigation
- Tachypnea, dyspnea
- Pruritus (flashing)
- Skin changes (hyperemia, ulceration, spots, trauma)
- Hyporexia
- Abnormal posture or swimming
- Mortalities
11
Q
Describe the diagnostics and treatment of fish in quarantine.
What are some of the common health problems acquired in quarantine?
What diagnostics should be considered?
What are some generalizations for whether an animal will have sensitivity to drugs?
What monitoring and filtration changes need to be done when systems go on immersion treatments?
A
Diagnostics and treatment
- Common categories of problems during quarantine
- Trauma
- Ammonia toxicity
- Poor feeding response
- Protozoal ectoparasites (esp crypto and ich)
- Monogeneans
- Opportunistic bacteria
- Viral infections, e.g. nervous necrosis virus, herpesvirus, lymphocystivirus;
- Oomycetes secondary to skin damage
- Metazoan endoparasites
- Crustaceans and other large ectoparasites (copepods, leeches branchiurans)
- Diagnostics
- PE, skin scrape, fin and gill biopsy
- Direct examination of ectoparasites
- Direct fecal
- Aspirates or scrapes of lesions
- Blood sample or aspirate of an effusion for bacterial culture;
- PCR for common viruses ie koi herpes virus
- Necropsies should always be carried out on mortalities during quarantine
- Ancillary testing such as cultures, histology, and other tissue analyses can be frustratingly slow with an emerging group issue in quarantine but can be invaluable in understanding the process, even in retrospect
- Reactive treatments can be targeted to the known diagnosis or the most likely diagnosis
- Supportive care
- Antibiotic therapy
- Praziquantel immersion and/or orally;
- Formalin immersion for freshwater and marine teleosts
- Copper sulfate or chelated copper immersion for marine teleosts;
- Chloroquine immersion for marine teleosts.
- Sensitivity to medications depends on a wide variety of factors, including species, life stages, overall health, temperature, water chemistry, microbiome, drug source, dosing regimen, and other stressors.
- Juveniles often show greater sensitivity to drugs
- Elasmobranchs show greater drug sensitivity
- Some species are sensitive to handling (ie sygnathids)
- Scaleless and fine-scaled teleosts may show a greater sensitivity to immersion medications, as do fish with skin lesions
- Bioassays (testing the drug on a subset of the population) can be invaluable in identifying any unexpected consequences of treatment
- Whenever immersion medications are used, environmental parameters should be monitored closely and contingency plans should be available in the event of filter damage, dissolved oxygen concerns, or a potential drug reaction in the fish
- Life support systems can alter immersion medications. In general, ultraviolet and ozone disinfection, activated carbon filtration, and foam fractionation should be discontinued or taken off-line for the duration of an immersion treatment
- Ozone can cause toxic metabolites so recommend carbon filtering after completion of treatment
12
Q
What records should be kept during the quarantine process?
Describe the risk assessment approach to fish quarantine.
What are the four broad categories and what measures should be considered for each?
A
Accurate records
- Important for quarantine evaluation - includes things like source, transport condition, species and number on arrival, behavior notes, morbidity and mortality etc
Risk assessment approach
- No quarantine is a one size fits all, risk assessment must be done on a variety of factors
- Water source, fish source, species and life stage, transport conditions, time of year, diet available, facilities available, history of collection, geographic area, quarantine and collection goals
- It is possible to use a risk assessment approach to anticipate likely problems and plan for specific diagnostics and preventative or reactive treatments
- Risk assessments are best done on a group-by-group basis
- Once potential problems have been identified, they can be categorized based on their cost (both financial and meaning loss of fish or welfare costs etc) and probability
- 4 broad categories:
- High cost and common, where preventative measures should be considered
- High cost and uncommon, where screening should be considered;
- Low cost and common, where screening should be considered
- Low cost and uncommon, where routine monitoring should be sufficient.
5 examples summarized in tables below. See chapter for full recommendations of each example based on six category model
13
Q
What are some of the common treatments used in the quarantine of fish?
How are freshwater/salwater dips used? What salinity is used? What species should not receive salt baths?
What is the benefit of using long-term low dose salinity in freshwater fish undergoing quarantine?
What is copper used to treat? What animals is it toxic to?
What is chloroquine used to treat? What additional considerations need to be made?
What is formalin used for? What is it toxic to? What environmental parameter needs to be monitored during its use?
What is praziquantal used for? How is it administered?
What about organophosphates? Toxicity is a concern in what species?
How are nematodes treated?
What vaccines may be used in a quarantine setting?
A
TREATMENTS FOR FISH
- Salt/fresh water dips
- Treats ectoparastes
- Short term immersion up to 5 min
- Marine fish 0 g/L salinity, freshwater fish 27-30 g/L salinity
- Tolerated well by most species- many catfish do not tolerate salt
- Long term, low dose salinity
- Reduce osmotic stress in fresh water teleosts, reduce uptake of nitrites
- Long term at low salinity of 1-4 g/L
- Well tolerated by most fish
- Copper
- Treats ectoparasitic ciliates and flagellates
- Long term immersion
- Treatment for cryptocaryon
- Toxic to invertebrates, elasmobranchs, and plants
- Immunosuppressive
- Chloroquine diphosphate
- Treates ectoparasitic ciliates and flagellates (cryptocaryon, amyloodinium)
- Long term immersion
- Darken tank during treatment
- Personnel protective equipment required
- Formalin (37% formaldehyde)
- Treats ectoparasitic ciliates and flagellates (esp. Ichthyophthyrius)
- Short and long term immersion
- Toxic to invertebrates, elasmobranches, plants, scaleless fish
- Decreased DO- need to supplement with oxygen in system
- Personnel protective equipment required
- Some products FDA approved in finfish
- Praziquantel
- Treats monogeans, digenetic tremetodes, cestodes
- Short and long term immersions
- Predissolve drug in ethanol helps dissolution
- Oral and intramuscular also an option, but doses vary
- Well tolerated at low to moderate doses
- Organophosphates (Dylox) and chitin inhibitors (dimilin)
- For parasitic infections not responsive to other methods (ie leeches, copepods)
- Short term immersion
- Dylox = trichlorfon, Dimilin = diflubenzuron
- Toxic to most inverts and potentially toxic to many other species
- Personnel protective equipment required
- Disposal of waste water regulated
- Fenbedazole/Levamisole
- Treats gastrointestinal nematodes, little effect on encysted stages
- Levamisole may be immunostimulant
- Immersion, IM, PO
- Caution with fenbendazole in bottom feeders
- Levamisole can damage biofilters
- Antibiotics
- Licensed for fish- florfenicol, oxytetracylines and potentiated sulfonamides (specific ones) licensed in catfish and salmonids
- Treat bacteria
- Immersion, IM, PO, or intracoelomic
- Can damage biofilters
- Waste water disposal regulated
- Vaccines
- Immersion vaccines available for:
- Vibrio anguillarum
- Aeromonas salmonicida
- Yersinia ruckeri
- Flavobacterium columnare
- Infectious salmon anemia virus
- Immersion vaccines available for:
14
Q
Describe the biosecurity measures that should be in place to keep fish healthy.
What external barriers can be in place to prevent the introduciton of disease into a population?
What internal barriers can be used?
What are four pathogen inactivation strategies?
A
Noga Ch 6 Health Management
Intro
- Proactive health management strategies are playing a greater role in aquaculture
- Also involves minimizing environmental impacts of the culture operation and, when dealing with food fish, ensuring that the product is safe for human consumption
Biosecurity
- Vital to reducing the risk of acquiring a disease in a facility
- External barriers
- Prevent the spread of pathogens onto and off of a farm
- Using a specific-pathogen-free (SPF) water source when possible
- Never introducing fish from other farms or at least never introducing fish from farms having older or less healthy fish
- Restricting the movement of fish between farm sites of the same operator
- If new fish must be introduced, using SPF fish or at least those with a known history of health. The history of the fish will also dictate the quarantine procedures needed
- Strict sanitary measures for all persons (including farm workers and visitors) entering the farm
- Restricting access to the farm site (e.g., fencing the site, locking all doors, restricting visitors, etc.)
- A pest management control program
- A feed hygiene program
- Internal barriers
- Prevent spread of pathogens within a farm
- Partitioning the farm into isolation units
- Physically separating each nit and keeping all units isolated from each other
- Having specific sanitation and personnel hygiene protocols
- Having specific sanitation protocols for movement of fish or materials between units
- Pathogen inactivation strategies
- Disinfection
- Must be practiced throughout the production cycle to eliminate pathogens on rearing nits, equipment, water, and even certain feeds such as live brine shrimp
- Antisepsis
- Treatment of fish and eggs with antiseptics is an important component of disease management
- Only effective against some skin or gill pathogens (ie prophylactic salt or formalin treatments)
- Fallowing
- Removal of all fish from a culture site to case the elimination (natural death) of a pathogen from the site
- Can be a very effective strategy as long as the microbe is an obligate fish pathogen
- Inhibiting fish to fish transmission
- Geographic isolation of farms
- Limiting human access to farms
- Separation of age classes
- Disease resistant strains
- Breeding fish strains that are resistant to pathogens - little progress has been made in this area
- Hybrids can also be superior in terms of resistance to stress and disease
- Specific-pathogen-free stocks
- The absence of a certain pathogen in a fish population
- Development of SPF stocks has advanced the most in salmonids and zebrafish
- Disinfection
15
Q
How is health promotion and maintenance accomplished in fish production?
What routes can vaccines be given to?
What immunostimulants are used to boost the health of fish?
What biological controls can be used to reduce pathogens?
How is animal health monitored?
How is animal welfare monitored?
A
Health promotion and maintenance
- Vaccines
- Salmonid industry has lead the way in vaccination efforts, but many vaccines can be given to a number of species
- Hugely useful in disease risk management
- Special considerations:
- A large number of vaccines can be expensive
- Time of vaccination must be closely correlated with immune status (ie can’t be given when they’re too young or will be ineffective)
- Environmental conditions such as temperature can be crucial for vaccine efficacy and immune response
- Health status - the manipulations involved in vaccination are stressful and can provide an opportunity for latent or opportunistic pathogens
- 3 routes used to vaccinate fish
- Waterborne–useful for large colonies, but not cost effective for large fish, protection for 3-12 months which is often not long enough for the production cycle of some fish
- Injection - often used in more valuable fish. Impractical in fish smaller than 5 grams
- Oral - used least commonly as they are not hooghly protective and also not cost effective for larger fish
- Only healthy fish should be vaccinated, should not be vaccinated within 21 days of slaughter or release
- If there is no commercially made vaccine, autogenous vaccines can be effective, though regulations vary within the US about their use
- Nonspecific immunostimulants
- Nonspecific immunity seems to be especially important in fish
- A number of drugs and microbial prod- ucts (e.g., levamisole, lipopolysaccharide, peptidoglycan, killed bacteria) can experimentally “turn on” nonspecific immunity and thus act as an immunostimulant.
- Commercial products are used either alone to “boost” fish immunity or in combination with vaccines
- Probiotics/competitive exclusion
- Experimental studies have shown that administering some live bacterial strains to fish can protect against pathogenic bacteria, but data are lacking from controlled field trials
- Biological Control
- The use of an organism to specifically prey upon, parasitize, or otherwise reduce the levels of an undesirable organism (usually a pest)
- Important that it only kills or preys upon the pest and doesn’t harm non-target organisms
- Best known example are cleaner wrasses, which remove ectoparasites and other material from other fish
- Health monitoring
- Day to day operations
- Aquaculture operations should have a predetermined routine monitoring schedule that includes water quality testing, inspecting fish for signs of disease, and randomly sampling moribund and/or asymptomatic fish for routine diagnostics
- Helpful to have a sentinel animal program by placing a group of fish in a location where they will be exposed to most or all of the effluent water from the culture systems
- Animal identification
- Individual identification becoming more mandatory
- Microchip is one of the most useful options
- PIT tags also sed
- Day to day operations
- Animal welfare
- Still controversial whether fish feel pain or not
- Welfare based around the 5 freedoms
- Conditions should be tailored to a particular species, life stage, and environmental setting
- To facilitate day to day evaluation of fish welfare, several simple indicators have been proposed: color, ventilation rate, swimming pattern, food intake, growth rate, BCS, presence of morphological abnormalities, injury, disease, reproductive performance
