aquatics (fish only) Flashcards
variations in fish physiology and anatomy - questions to ask yourself when assessing/deciding treatment for a fish
what species?
diet - herbivore/carnivore/omnivore?
(internal anatomy depends on this)
what is anatomically normal?
(e.g. moray eels have pharyngeal jaw)
what is behaviourally normal?
what’s their wild habitat like?
external anatomy of fish: 6 elements
operculum
lateral line
caudal fin
dorsal fin
anal fin
pectoral/pelvic fin
external anatomy -
operculum
protective gill cover
involved in ‘buccal’ pump for respiration
external anatomy -
caudal fin
largest and most powerful
forward momentum
external anatomy -
dorsal fin
keeps fish upright
controls direction of movement
external anatomy -
anal fin
not all fish?
additional (to dorsal) to keep fish stable and upright
external anatomy -
pectoral/pelvic fins
steering
balance
moving up/down in water
external anatomy - lateral line
system of sense organs used to detect movement, vibration, pressure gradients
fish - functions of skin
- barrier to env
- osmotic barrier
- lubrication
- defence against pathogens
why is constant handling an issue for fish?
handling = removes mucus from skin = mucus offers protection e.g. from pathogens = skin issues
INTERNAL ANATOMY
GI tract
simple and short in… a)
longer in… (b)
a) carnivores (rapid digestion and absorption)
b) herbivores (trying to get as much nutrients from plants)
INTERNAL ANATOMY
kidney
- large species variation
- can be 2 structures (w sep functions) or 1: anterior and posterior kidneys
NOTE: function of each kidney may varies species to species
INTERNAL ANATOMY
anterior kidney for…
osmoregulation
excretion of waste
NOTE: function of each kidney may varies species to species
INTERNAL ANATOMY
posterior kidney for…
hematopoiesis (blood cell prod)
immune function
NOTE: function of each kidney may varies species to species
GILLS
(5 FUNCTIONS)
GAS EXCHANGE
ACID-BASE BALANCE
EXCRETION OF NITROGENOUS WASTE (not wee, some fish can actually wee)
OSMOREGULATION (ION EXCHANGE)
IMMUNE ROLE
DEFINE OSMOREGULATION
the maintenance of constant osmotic pressure in fluids of an organism
by the control of water and salt concentrations
osmoregulation in fish-
how much of a fish’s total energy output is used for osmoregulation?
25-50%
osmoregulation in fish-
organs/body parts involved?
1 kidney
2 gut
3 gills
osmoregulation - SALT water fish
- env is hypertonic/hypotonic to fish?
- so, water ___________ __________ fish
- salt obtained from?
- salt excreted via?
- hypertonic
- passively LEAVES
- drinking large quantities of salt water
- urine/gills/dig tract
osmoregulation - FRESH water fish
- env is hypertonic/hypotonic to fish?
- so, water ___________ __________ fish
- salt obtained from?
- salt excreted via?
- hypotonic
- passively ENTERS
- food
- high vol of urine w low salt content
heart
receives __________ from ___________
and then?
ox. blood from gills
then pumps around body
(have an atrium and vent)
what is a swim bladder?
(organ?)
maintaining buoyancy and position
not present in all species
water quality - most important factors
- oxygen/CO2
- nitrogen cycle (ammonia, nitrate, nitrite)
water quality - low oxygen
leads to… (3)
(respiratory distress)
gasping
gathering at areas of higher O2 (water inlets)
flared gills
2 sources of CO2 in fish tanks:
fish resp.
decomposing matter
CO2 concs: day vs night
(daily fluctuation opp to oxygen)
decreases during day
increases during night
why is a high CO2 conc in water a bad thing?
high CO2 conc = fish can’t excrete through gills (due to conc gradient??) = CO2 builds up in blood
countermeasure for high CO2 levels in tank
aeration
water quality -
use the nitrogen cycle to explain why water should be changed on a weekly basis
fish waste+food/decomposing animals+plants = ammonia
TOXICITY: AMMONIA > NITRITE > NITRATE
biological filter has denitrifying bacteria to convert ammonia to nitrite (less toxic but still harmful - brown blood disease)
denitrifying bac in bio filter convert nitrite to nitrate (least toxic form)
still toxic/high levels = reason why weekly water changes are needed
new tank syndrome
people buy too many fish, not enough denitrifying bac (immature biofilter)
fish eating = ammonia
ammonia = toxic
fish death = more ammonia
= more fish die
need to start with low no e.g. 1-2 fish and increase approx 4 weeks
treating fish - factors to consider/investigate on diagnosis?
- water quality
- diet
- stocking density
- lighting
- signs of illness
- indiv or group? how many are showing signs?
- necropsy*
when examining fish - what to look for
- check skin
- check respiration (gill/opercula movements)
- swimming patterns
- observe interactions between fish
2 common sampling (?) methods during exam
skin scrapes
gill clips
(can send samples off to lab/for analysis?)
diagnostic imaging that can be used
radiographs
ultrasounds
anaesthetics (3)
[MS-222 AK] Tricaine
(powder dissolves in water, buffer with Bicarbonate (baking soda), 1:1 ratio)
2-phenoxyethanol (aqua-sed)
(1 pump/L water, species variation, euthanasia = quadruple dose (4 pumps/L)
Eugenol
(Clove oil)
common conditions - ‘dropsy’
THIS IS NOT A DISEASE, BUT A CLINICAL SIGN
caused by fluid build up in body, problems with osmoregulation
= buoyancy issues
often issue with swim bladder (due to water qual?)
common conditions in fish
1st is clinical sign not condition
then (4)
- dropsy
- tumours
- infectious diseases
- egg binding/dystocia (female)
- polycystic kidneys
blood sampling in fish:
- in tail vein, ventral to spine, (see onenote for photo) needle at 90/45 degree angle
why use zebrafish as research models?
- genetic similarity to humans
- ease of care
- easy to see impact of gen mut. or drug (transparent embryo and larvae)
- high no.s of offspring
- easier to introduce genetic changes
