aquatics (fish only) Flashcards by Jennah Khan

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?

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external anatomy of fish: 6 elements

operculum

lateral line

caudal fin

dorsal fin

anal fin

pectoral/pelvic fin

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external anatomy -

operculum

protective gill cover
involved in ‘buccal’ pump for respiration

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external anatomy -

caudal fin

largest and most powerful
forward momentum

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external anatomy -

dorsal fin

keeps fish upright
controls direction of movement

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external anatomy -
anal fin

not all fish?
additional (to dorsal) to keep fish stable and upright

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external anatomy -
pectoral/pelvic fins

steering
balance
moving up/down in water

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external anatomy - lateral line

system of sense organs used to detect movement, vibration, pressure gradients

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fish - functions of skin

barrier to env
osmotic barrier
lubrication
defence against pathogens

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why is constant handling an issue for fish?

handling = removes mucus from skin = mucus offers protection e.g. from pathogens = skin issues

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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)

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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

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INTERNAL ANATOMY

anterior kidney for…

osmoregulation

excretion of waste

NOTE: function of each kidney may varies species to species

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INTERNAL ANATOMY

posterior kidney for…

hematopoiesis (blood cell prod)

immune function

NOTE: function of each kidney may varies species to species

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GILLS
(5 FUNCTIONS)

GAS EXCHANGE

ACID-BASE BALANCE

EXCRETION OF NITROGENOUS WASTE (not wee, some fish can actually wee)

OSMOREGULATION (ION EXCHANGE)

IMMUNE ROLE

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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