Lecture 3 Flashcards
Why do we collect samples
Investigating
- Sudden death
- Signs of disease
- increased mortalities
- Disease surveillance
- Disease investigation
What tests can be done
- Culture of bacteria
- Culture of viruses
- Molecular biology test to detect fish pathogens
- Examination of fish tissues for pathological changes -histopathology
- Blood chemistry
What types of fish should be sampled
Moribund fish with signs of disease
Choose fish that have examples of key lesions or signs of disease
Usually font sample dead fish
How many fish should be sampled
- to find a disease - at least 5-10 fish with signs of disease from affected tank or cage where possible, a separate submission form for each tank or cage
- To prove freedom of a disease - individuals or pools of 5 fish from representative samples, usually for survallance purposes
Where are the best samples collected from
At a well prepared work station on-shore
Where to collect fish from for testing
Ideally, collect fish from cages/ponds and place them in individual labelled plastic bags and place in containers with crushed ice
Bring the fish back to shore within 3-4 hours of collection
Keep the time between collection and sampling as short as practicable
Storage methods for sample material
Culture plates
Keep plates away from cooling elements in fridge, otherwise they will ‘sweat; and can become contaminated
Store places separately to any formalin pots
What are some importances with instruments
Keep dissection instruments clean; use only for dissection
Make sure you have duplicates of instruments - sterile
Buy good quality instruments
What is it important when collecting samples
Think ahead
Where are you going to be able to take a sterile sample
What sort of fish to take blood samples from
Use moribund liver or healthy live fish for collecting blood samples
What are the blood collection tubes
Heparin for haematology
Plant blood tubes for biochemistry and serology
How to collect blood
Syringe and needle
- Often the needle and syringe are flushed with heparin first
- 26g needle and a 3-5ml
How to collect blood from fish
Insert needle at a 90 degree or 45 degree angle cranially on the ventral surface of the caudal peduncle until the vertebrae are just reached
Pull back the needle slightly and withdraw plunger gently until blood begins to flow
Remove needle from syringe and gently expel blood into blood tube and/or slide
What is the procedure after collecting blood
If required for haematology, make a blood smear on a glass slide by placing a drop of blood at one end of the slice and making a film by drawing the blood across the slide with a second angled slide
Bacteriology: what are preferred for sample qualities
Moribund fish are the preferred sample
Where possible sample at least 5 fish
What are the precautions to take with bacteriology
Quality of sample affects quality of results
Use aseptic procedures for collecting samples
Don’t leave plates uncovered or exposed to the sun
Check media expiry date and condition of media
Have the media been stored refrigerated
Do not use media if expired, contaminated or has been frozen
Bacteriology culture: what are BA/TCBS used for
Internal sights: kidney, brain, gut, eye
Bacteriology culture: what are BA2%/SS used for
External sights: skin and gill lesions
What is the big thing with virology
Need to let lab know to get thing up and running Submit on ice and fresh NB to be aseptic Do this in a good location Dont expose to sunlight
What is the preferred sample for virology
Whole fish on ice
What are the precautions for microbiology
Aseptic procedures for collecting samples
Keep collected samples cool at all times to converse nucleic acids
Use correct medium for samples
Normal behaviours of fish
coughing flashing piping circling or whirling drifting abnormal
What to check fins for
Erythema, excess mucous, trauma or physical damage
What to identify and examine
the pseudobranch the gill rakers individual hemibranchs the branchiostegal membrane the lateral line the vent the pelvic cartilage (know where it is) the nares he 4 gill arches
