Fish

Question 1

Name all the fins and their function

Answer 1

Dorsal fin= stabilise the animal against rolling and assist in sudden turns

Adipose fin (behind dorsal only salmon, catfish) = research into whether it’s sensory

Upper and lower caudal fin= propulsion

Anal fin= stability while swimming

Pelvic fins = assists with going up and down through water

Pectoral fins = breaking and steering, associated with lift and walking in some species e.g. Mudskipper

Question 2

What 3 fish types can you get and give an example of each

Answer 2

Jawless e.g. Sucker fish

Cartilaginous e.g. Shark

Boney e.g. Clown fish

Question 3

Give some information regarding the history and success of fish

Answer 3

The bony fish are the most successful vertebrae group (most species, greatest biomass, greatest numbers). Even more than mammals.

These fish have evolved in poor oxygen environments and are able to generate very high oxygen levels in several tissues including the eye.

Fish haemoglobin and local control of pH may also play a role.

They live in marine and fresh water environments and also are vertically distributed too (mountains and occean abyss)

Question 4

How do fish survive freezing temps?

Answer 4

Antifreeze molecules (glycoproteins) in blood which reduces the freezing point of body fluids.

They also reduce their metabolic rate

Water on the bottom is also insulated

Question 5

Give some facts about fish repro

Answer 5

Can reproduce in many ways e.g. Open water spawning, spawning in nests, viviparous, oviparous

Many types of relationship e.g. Monogamous and polygamous

Reproductive rate varies between species

Fish can be hermaphrodytes

Asexual repro can occur in species containing females only

Some show sexual dimorphism (dif betwen M and F)

Paternal care varies with spp

Question 6

Describe the anatomy of the gills

Answer 6

Found when you lift the operculum

4 cartilaginous bony “gill rakers” made up of arches

Gill filaments attached.

Gill filaments are composed of lamellae, which in turn are made of thin epithelial cells.

They are so red in colour due to haemoglobin for oxygen transport

Question 7

Compare the eye of a fish to that of a mammal

Answer 7

Fish have a more spherical lens

There lens is camera lens

Question 8

What is the lateral line?

Answer 8

It is a primary sensory organ

A row of sensory cells able to pick up vibrations in the water

Determines direction of source of vibrations so helps in hunting or avoiding predators

Essential to fish living in dark

Question 9

What causes fish health issues?

Can the majority of these be prevented?

Give 2 reasons why fish are of vet importance

Answer 9

Poor water quality, trauma, poor nutrition and pre existing disease

Yes 90% of healthcare problems could be prevented

Important as worth a lot of money and also important in terms of FOOD SAFETY

Question 10

Give some key points about quarantine

Answer 10

Needs to last 30-90 days
Check fish in and out
Post mortem if die
If disease occurs prolong quarantine 
Use designation equipment

Question 11

Give an example of a problem in fish farming

Answer 11

In salmon farming, huge losses due to skin-parasitic crustcean, causing ulcerative lesions. Cost industry 14 million euros a year

Question 12

How do you PTS a fish

Answer 12

Concussion to brain by striking cranium
Or
Overdose

Question 13

Why is filtration so important

Answer 13

Removal of toxic ammonia which is produced by the fish from the gills and urine and also from decay or faeces and solid waste.

Question 14

What 3 types of filtration are there and how do they work?

Answer 14

Mechanical = trap solids

Biological = aid growth of beneficial bacteria which remove nitrogenous waste by nitrification (ammonia-nitrite-nitrate) e.g. Nitrosomonas spp

Chemical = adsorb undesirable substances from water e.g. Locked by carbon granules remove phenols

Question 15

State a few things a biological filter needs

Answer 15

Oxygen for nitrification to occur
Not to be cleaned in tap water (Cl kills bact)
Dark (light inhibits bact)
Small amount of ammonia as food

Question 16

Why is mechanical filtration needed if using chemical

Answer 16

Solids can block the pores of the medium

Question 17

How do open, semi closed and closed systems vary?

Answer 17

Open have no water quality management

Closed has lots

Question 18

Describe what the internal anatomy looks like

Answer 18

Stomach is just an extension of the oesphag - trace it down to the central part of the fish and this part is the stomach (still just a tube)

Liver is immediately under the skin (look like lungs- but remember NO lungs in fish)

Pyloric caecae= all the tissue surrounding the stomach and intestines (hard to distinguish)

Swim bladder = see through bag filled with air

Kidney = very long red organ between the swim bladder on the dorsal aspect

Question 19

What is the function of the swim bladder

Answer 19

Fills with various amounts of gas

Changes fishes density in water and therefore effects buoyancy

The muscles of the fish relax, allowing more space for air to move in

Question 20

What does the kidney of the fish do?

Answer 20

Excrete nitrogenous waste

Question 21

Do fish have a gall bladder?

Answer 21

Yes- found under liver, stores yellow fluid = bile

Question 22

How many chambers does a fish heart have compared to a mammal?

Answer 22

Fish has a two chambered heart (atria and a ventricle)

Mammal has 4

Question 23

Where could you take bloods from in a fish?

Answer 23

Caudal peduncle at base of tail

Question 24

What is the best way to measure a fish

Answer 24

Standard length (top of nose to base of tail) as tails can be altered by trauma or disease

This is better than measuring Fork length

Question 25

What do you call internal support elements/bones that support the dorsal fin?

Answer 25

Pterygiophores

Question 26

What is the function of the swim bladder

Answer 26

It allows the fish to conserve energy by maintaining neutral buoyancy

If species don’t possess them, then they have to swim to stay up from the bottom

Goldfish are prone to swim bladder problems.

Question 27

Describe the form and function of the fish skeleton and muscles

Answer 27

Vertebrae are either caudal or abdominal, they have a highly ossified skull. They have a backbone and ribs.

There muscles of the tail and trunk are composed of blocks called myotomes. These are separated by myosepta. These muscles are the main driving force for swimming. Sides contract one by one producing swimming action. They have white and red muscle as with mammals. White for short bursts, red for long duration.

Question 28

Describe the cardiovascular system of a fish

Answer 28

The cardiovascular system of a fish can be thought of as a loop. (Body heart gills repeat)

Blood is used in the body and passes to heart. Heart pumps this to the gills to be oxygenated. Them goes to the body again and repeats.

The heart of the fish has 2 chambers (atria and ventricle) with a part either side: sinuous venosus-a-v-conus arteriosus

They have nucleated RBCs (like birds they evolved in the Jurassic era)

Blood vessels are a “closed system”

Question 29

Describe the fish respiration system

Answer 29

Gills are used for respiration.
They are also used to move fluids and minerals into or out of the fish.
Exchange occurs by means of a countercurrent system (water flows over the gills in a different direction to the blood flow in the gills)
For this to continue to working you need a constant flow of oxygen rich water to ventilate the gills
To ensure this, fish allow water to flow into their mouth, contract the Buccal cavity and expands the operculum letting water shoot out over the gills

Question 30

Sharks and rays use another technique- what do they do?

Answer 30

They use flaps of skin to create currents to aid respiration

Question 31

What do fish do in low oxygen?

Answer 31

Increase freq of buccal/operculum ventil

Gulp water at surface which is higher O2

Some species can breathe air, breathe through skin etc.

Question 32

What is the function of the kidney?

Answer 32

It filters out liquid waste from blood, and out of the body

Important in regulating water and salt concs allowing fish to live in salt/fresh water

Question 33

Explain osmoregulation by the kidney and salt regulation…

Answer 33

Salt water fish have chloride cells in their gills which produce the enzyme Na/K/ATPase
In salt water, they gain ions and water from food and by drinking it
The enzyme uses energy and pumps out Na
Water follows the sodium (osmotic loss)
Kidneys selectively filter out Divalent ions which they then excrete
Therefore they lose small amounts of concentrated urine as water is lost with ions

Fresh water fish, eat/drink, they actively uptake ions and therefore water, they therefore excrete lots of water so have large amounts of dilute urine

Question 34

Explain the nitrogen cycle in the tank

Answer 34

Ammonia from waste/uneaten food
Breaks down to NH4 and NH3
NH3 is toxic
Nitrosomas bacteria oxidise ammonia to nitrates and nitrobacter will convert nitrites to nitrates
These are still toxic though
Partial water changes stop these getting to a toxic level

Question 35

Describe the digestive system of a fish

Answer 35

Stomach and intestine digest food and absorb nutrients
Depending on what they eat, depends on time it takes=
Other fish-quickly and easily chemically broken down
Plant material- tough and fibrous, more difficult to break

Question 36

The pyloric caeca is found at the junction of stomach and intestines. Remember it’s pretty much everything but these things. Describe it, and what do people think it does?

Answer 36

Finger like projections

Secretes enzymes and maybe absorbs digested food

Question 37

What’s the function of the liver?

Answer 37

It assists in digestion by secreting enzymes which breaks down fats
Serves as a store for fats and carbohydrates
Important for the destruction of RBCs (maintaining blood chem)
Plays a role in nitrogen waste excretion

Question 38

How do you sex a fish?

Answer 38

Opening it up

Taking bloods

Question 39

Many fish are species differences e.g. Single or paired gonads, do ducts. Both flow into the cloaca.
How does the testes and ovary differ?

Answer 39

Testes ducts flow through kidney

Ovary is not attached to mullers duct. It’s separate. It’s ciliates though, that’s how the egg is caught