Lecture 3

Question 1

Why do we collect samples

Answer 1

Investigating

• Sudden death
• Signs of disease
• increased mortalities
• Disease surveillance
• Disease investigation

Question 2

What tests can be done

Answer 2

• Culture of bacteria
• Culture of viruses
• Molecular biology test to detect fish pathogens
• Examination of fish tissues for pathological changes -histopathology
• Blood chemistry

Question 3

What types of fish should be sampled

Answer 3

Moribund fish with signs of disease
Choose fish that have examples of key lesions or signs of disease
Usually font sample dead fish

Question 4

How many fish should be sampled

Answer 4

1. 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
2. To prove freedom of a disease - individuals or pools of 5 fish from representative samples, usually for survallance purposes

Question 5

Where are the best samples collected from

Answer 5

At a well prepared work station on-shore

Question 6

Where to collect fish from for testing

Answer 6

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

Question 7

Storage methods for sample material

Answer 7

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

Question 8

What are some importances with instruments

Answer 8

Keep dissection instruments clean; use only for dissection
Make sure you have duplicates of instruments - sterile
Buy good quality instruments

Question 9

What is it important when collecting samples

Answer 9

Think ahead

Where are you going to be able to take a sterile sample

Question 10

What sort of fish to take blood samples from

Answer 10

Use moribund liver or healthy live fish for collecting blood samples

Question 11

What are the blood collection tubes

Answer 11

Heparin for haematology

Plant blood tubes for biochemistry and serology

Question 12

How to collect blood

Answer 12

Syringe and needle

• Often the needle and syringe are flushed with heparin first
• 26g needle and a 3-5ml

Question 13

How to collect blood from fish

Answer 13

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

Question 14

What is the procedure after collecting blood

Answer 14

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

Question 15

Bacteriology: what are preferred for sample qualities

Answer 15

Moribund fish are the preferred sample

Where possible sample at least 5 fish

Question 16

What are the precautions to take with bacteriology

Answer 16

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

Question 17

Bacteriology culture: what are BA/TCBS used for

Answer 17

Internal sights: kidney, brain, gut, eye

Question 18

Bacteriology culture: what are BA2%/SS used for

Answer 18

External sights: skin and gill lesions

Question 19

What is the big thing with virology

Answer 19

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

Question 20

What is the preferred sample for virology

Answer 20

Whole fish on ice

Question 21

What are the precautions for microbiology

Answer 21

Aseptic procedures for collecting samples
Keep collected samples cool at all times to converse nucleic acids
Use correct medium for samples

Question 22

Normal behaviours of fish

Answer 22

coughing 
flashing 
piping 
circling or whirling 
drifting 
abnormal

Question 23

What to check fins for

Answer 23

Erythema, excess mucous, trauma or physical damage

Question 24

What to identify and examine

Answer 24

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