Fish medicine Flashcards
Role of a vet in the aquatic animal industry?
- Health management & disease prevention
- Aquaculture and food safety
- Conservation and wildlife health
- Regulatory and policy roles
- Education & training
- Ornamental fish and public aquariums
- Research & conservation of aquatic ecosystem
- Exotic species and zoonotic dx control
What important consideration?
VENOMOUS SPECIES
what notes on initial contact ?
- Advise client to send pictures of set up & history
- Ensure staff prepared -> block off time to examine +/- diagnostics
- Advise on transport & what to bring (separate bags of water, spare acquarium bags, sealed container with water, for testing)
How can we be ‘fish ready’
- Willing vet/RVN
- High quality microscope
- Slides/coverslips
- Hand held lens
- Powder free gloves
- Basic surgical kit
- Water testing kit -> API freshwater master test kit
When would we do home visits/ why?
● For larger set ups/outdoor ponds.
○ Full assessment easier → can see bigger picture.
■ Filtration methods → biological vs mechanical.
■ Water quality → appearance, smell, temperature, aquatic plants,
algae growth.
■ Stocking density.
What biosecurity to remember?
● Remember to take microscope!
● Remember to take basic equipment for sedation for pond side diagnostics
What biosecurity to be aware of?
■ Koi herpes virus (Cyprinid herpesvirus 3) → notifiable
■ Spring Viraemia of Carp → notifiable
Quarantine ?
○ Isolate new fish for 30-90 days before introducing them to the main tank.
○ Use a separate tank with proper filtration and heater.
Maintenance of water quality?
○ Perform regular visual inspections and water quality tests.
■ Test ammonia, nitrite, nitrate, dissolved oxygen, temp and pH levels regularly.
■ Ammonia should be 0mg/l. Nitrite should be 0mg/l.
■ Nitrate is less toxic BUT levels of 50mg/l & above may be LETHAL to some
species.
■ Nitrate is more toxic in salt water & at a low pH.
How often to change water?
Perform 10-30% water changes weekly or bi-weekly, depending on set-up/species
How to remove chlorine?
use water conditioners.natural emthods
New tank syndrome?
- NEW TANK MUST BE CONDITIONED BEFORE ANY FISH ADDED
- ADD TOO EARLY → RAPID SPIKE IN AMMONIA, NITRITES & NITRATES = DEATH
What to filtrations do we want?
Biological ->
- gravel or media within filter;
- bacteria within gravel converting ammonia -> nitrites -> nitrates
Mechanical ->
○ Use of water → water drawn in through media → traps waste
○ Must be cleaned regularly (10-14 days) with approx. 10%
water change weekly
Water changes?
○ Treat new water before adding
○ Treatment to remove chlorine, chloramines & heavy metals
How to ensure optimal filtration system?
○ Use of mechanical, biological and chemical filtration
(carbon).
■ If under treatment, carbon must be removed from
tanks
○ Clean or replace filter media as recommended.
○ Ensure the filter & flow rate is appropriately sized for
the tank.
What is appropriate stocking density?
○ Follow the guidelines for the species (marine fish →
lowest stocking density)
■ Based on water volume & surface area + fish
species
○ Ensure fish have adequate space to swim and hide.
○ Consider the bioload when stocking the tank.
Diet & feeding practices?
○ Feed a varied, species-appropriate diet.
○ Feed small portions and remove uneaten food.
○ Avoid overfeeding to prevent poor water quality.
tank cleaning?
○ Perform regular gravel vacuuming during water
changes.
○ Clean decorations and plants to remove algae.
○ Avoid drastic water changes that could shock the
fish.
Stability of environment ?
○ Maintain stable temperature and water conditions.
○ Provide hiding spots for fish to feel secure.
○ Place tanks in quiet areas to avoid stress from noise/vibrations.
routine health assessments?
○ observations for signs of illness (e.g., white spot, frayed fins, lumps/bumps).
■ Look for common signs of parasites, bacterial infections, and fungal diseases.
○ Any behavioural changes?
○ Appropriate handling – only when necessary.
■ Use a soft net and care when handling – minimise stress & physical damage.
■ Isolate and treat any sick fish in a quarantine tank.
History pt 1 ?
History pt 2?
History pt 3?
Describe how to do water testing?
○ API master kit → ammonia, nitrite, nitrate, pH, oxygen content
■ Ideally water should be tested onsite but if not possible get
client to bring a sealed, filled (clean) container of water.
■ Specific guidelines → measured volume added to
measured amount of chemical → colour change →
compare to chart
■ Don’t forget the temperature!
○ Low oxygen and poor water quality can stress fish and contribute
to disease.
Waterborne pathogen testing?
Culture, Colony, count, bacterial population, microscopy
Describe skin scrapes?
● Skin scrape → microscopy slide → scrape in direction of
scales to collect mucus →apply coverslip → examine
immediately.
● Collect from several areas to include under fins and the
underside of the fish
● Non invasive procedure
● Skin scrapes to identify parasites, fungi, or bacteria.
● Ideally perform without sedating
○ Immersion in anaesthetic agent may affect culture
and parasite observation
Gill clip procedure?
● Diagnostic procedure → under anaesthesia
● Healthy gills should be red
● Lift operculum and take a small sample of gill
filaments.
● Examine under microscope immediately.
○ Assess for parasites
○ Assess structure and cellularity of gills
Blood sampling approach?
Ventral or lateral approach to caudal vein
○ Lateral approach → insert just below lateral line angled
towards the head.
○ Ventral approach – ventral midline caudal to anal fin
how to do blood sampling ?
● Clean with dilute povidone iodine
● Insert needle between scales
● Fresh blood smears & heparin tube
● Haemolysis occurs readily in fish → use as little vacuum as
possible.
microsopic exam on faecal exam?
○ Normal faeces are dark green/brown (varies with
species/diet)
○ Normally break off after emerging from vent (freshwater) vs
not formed & disperses in water (marine fish)
○ Abnormal colouration → pale, white, yellow, mucoid
○ Abnormal → long, stringy and trails from vent.
○ Abnormal → may float to surface. may see blood.
what might we see on fresh smears?
Fresh smears → microscopic examination → Capillaria ova,
flagellate protozoans & coccidia depending on species
radiography?
○ Under sedation – orthogonal views
○ Useful for determining coelomic swellings/look for causes of buoyancy
problems
○ Great at visualising skeletal anatomy and position of swim-bladder
○ Can use contrast media – barium or iohexol for Gi tract (species
dependent – approx. 5ml/kg)
US in fish?
○ Differentiates soft tissue structures → organ size, location &
pathological changes
○ 7.5-10 MHZ transducer
○ Leave fish in water → no need for acoustic gel → use glove
○ Care!!! Electrical equipment & water – residual current device must be
used.
PME eval?
● In some circumstances (group) may need to
euthanise one.
● Aquased → 10 pumps/litre
● Perform PME within 1 hour
● Gill snips/skin scrapes/gross lesions
● Full post mortem – incision ventral midline
● Histopathology/culture & sensitivity testing
what is white spot?
(Ich) (Ichthyophthirius multifilii) common rotozoan parasitic infection in freshwater fish species
what do we see with white spot?
- Small, white spots over body.
- Excess of mucus and thickened epithelium
- Advanced disease → extensive gill damage. Typically introduced to aquariums through
infected fish or plants.
Life cycle of Ich?
- Free-swimming stage (theront) → locates host → penetrates the epidermis →
develops into a ciliated trophont → WHITE SPOT → breaks through epidermis and
becomes an encysted tomont → this attaches to tank furniture/plants → division →
release of infective theronts - Life cycle = 10-15 days at 15°C & 6 days at 27°C
marine equivalent of Ich?
Cryptocaryon irritans → Life cycle identical
Tx for ìch?
→ if identified before infective stages released → remove fish & quarantine
* Only the free-swimming stage is susceptible to chemical treatment → repeat treatments
needed at approx. 5-10 day intervals. Treatment intervals are temp dependent
what is ‘dropsy’?
non-specific term →oedematous conditions
in a fish.
what might we see with dropsy?
- Abdominal distension → ascites
- Cutaneous oedema → scales protrude
- Exophthalmos may be seen.
Causes / tx of Dropsy?
- A symptom of underlying issues, typically related to
failure of osmoregulation → gill or kidney disease. - Need to address underlying cause → if bacterial
infection may respond to antibiotics. - Polycystic kidneys/neoplasia – poor prognosis
What is Fin Rot?
affects their fins and in severe cases, can
progress to the body → peduncle disease.
* Often caused by bacterium Flavobacterium
columnare → affects debilitated fish
what do we see with fin rot?
Hyperaemia of the fins often seen → caused by
septicaemic infections.
Tx of fin rot?
→ treat underlying cause, remove
stressors, water changes, antibacterials if indicated,
?aquarium salt
surgical considerations?
● Thermoregulation, osmoregulation, and other water quality
parameters must be maintained.
● Postoperatively, depending on species and procedure, may want
to add salt to the water concentration of 3-5ppt (species variation)
for freshwater species → reduces osmotic stress.
Suture material in fish?
If using suture material, absorbable suture will remain for a longer
period of time → lower environmental temperatures
mass removal?
● Indication for surgery should
ideally be confirmed, before the
procedure as some masses will
regress spontaneously (cyprinid
herpesvirus 1 infection)
● External mass incisional or
excisional biopsies are similar to
that in mammals.
enucleation in fish?
Anaesthetise → lidocaine block → dissect and transect
periorbital tissue, conjunctiva and oculomotor muscles
off the globe.
● Transect and remove the globe.
● Ligate retro-orbital vessels, apply digital pressure and a
haemostatic gel if available.
● Leave the orbit open to heal by secondary intention
wound management?
Follow same principles as a more
familiar species.
● Culture and sensitivity
● Debride necrotic tissues, remove
detached scales
● Lavage wound
● Apply thin layer of gel
Dentals in fish medicine?
● Oral surgery and incisive plate
adjustments to aid in food prehension if
there has been insufficient wearing of
the dental plates or an oral mass.
● Pufferfish
→ continuously growing
incisor plates (normal!). If overgrown,
under a GA trim with a dental burr or
rotary tool.
● Care not to overheat the incisor plates ● Address diet to prevent this reoccurring
