Fish Flashcards
Name all the fins and their function
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
What 3 fish types can you get and give an example of each
Jawless e.g. Sucker fish
Cartilaginous e.g. Shark
Boney e.g. Clown fish
Give some information regarding the history and success of fish
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)
How do fish survive freezing temps?
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
Give some facts about fish repro
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
Describe the anatomy of the gills
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
Compare the eye of a fish to that of a mammal
Fish have a more spherical lens
There lens is camera lens
What is the lateral line?
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
What causes fish health issues?
Can the majority of these be prevented?
Give 2 reasons why fish are of vet importance
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
Give some key points about quarantine
Needs to last 30-90 days Check fish in and out Post mortem if die If disease occurs prolong quarantine Use designation equipment
Give an example of a problem in fish farming
In salmon farming, huge losses due to skin-parasitic crustcean, causing ulcerative lesions. Cost industry 14 million euros a year
How do you PTS a fish
Concussion to brain by striking cranium
Or
Overdose
Why is filtration so important
Removal of toxic ammonia which is produced by the fish from the gills and urine and also from decay or faeces and solid waste.
What 3 types of filtration are there and how do they work?
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
State a few things a biological filter needs
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
Why is mechanical filtration needed if using chemical
Solids can block the pores of the medium
How do open, semi closed and closed systems vary?
Open have no water quality management
Closed has lots
Describe what the internal anatomy looks like
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
What is the function of the swim bladder
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
What does the kidney of the fish do?
Excrete nitrogenous waste
Do fish have a gall bladder?
Yes- found under liver, stores yellow fluid = bile
How many chambers does a fish heart have compared to a mammal?
Fish has a two chambered heart (atria and a ventricle)
Mammal has 4
Where could you take bloods from in a fish?
Caudal peduncle at base of tail
What is the best way to measure a fish
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
What do you call internal support elements/bones that support the dorsal fin?
Pterygiophores
What is the function of the swim bladder
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.
Describe the form and function of the fish skeleton and muscles
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.
Describe the cardiovascular system of a fish
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”
Describe the fish respiration system
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
Sharks and rays use another technique- what do they do?
They use flaps of skin to create currents to aid respiration
What do fish do in low oxygen?
Increase freq of buccal/operculum ventil
Gulp water at surface which is higher O2
Some species can breathe air, breathe through skin etc.
What is the function of the kidney?
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
Explain osmoregulation by the kidney and salt regulation…
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
Explain the nitrogen cycle in the tank
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
Describe the digestive system of a fish
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
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?
Finger like projections
Secretes enzymes and maybe absorbs digested food
What’s the function of the liver?
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
How do you sex a fish?
Opening it up
Taking bloods
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?
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
