ANIMAL Husbandry - Fish Flashcards
What are the five main roles of vets in the aquaculture industry?
Health management
Training/education
Diagnostics
Research
Epidemiology
List two examples of commonly farmed salmonoid fish
Atlantic salmon
Trout
List two examples of commonly farmed freshwater fish
Carp
Tilapia
List three examples of commonly farmed marine fish
Cod
Sea bass
Halibut
Why is replicating the lifecycle of Atlantic salmon so challenging?
Replicating the lifecycle of Atlantic salmon is so challenging because Atlantic salmon undergo behavioural, physiological and developmental changes known as smoltification which allows them to transition from freshwater to seawater
Describe briefly the lifecycle of Atlantic salmon within aquaculture
- Eggs and milt (sperm) are stripped from broodstock and eggs are fertilised
- Eggs develop into alevins
- Alevins develop into pre-smolts
- Pre-smolts develop into smolts which will undergo smoltification and be ready to enter seawater
- Smolts will develop into growers
- Growers will be retained as broodstock or harvested
Describe briefly the lifecycle of trout within aquaculture
- Eggs and milt (sperm) are stripped from broodstock and eggs are fertilised
- Eggs develop into alevins
- Alevins develop into fry
- Fry develop into growers which may or may not undergo smoltification and enter seawater
- Growers will be retained for broodstock or harvested
Why are eggs and milt (sperm) stripped from the brooding stock in aquaculture?
To allow for selective breeding
What is an alevin?
An alevin is a newly hatched salmon or trout which is still carrying the yolk
What is meant by the ‘planktonic’ larval stage seen in some marine species? Why does this stage require live feedings?
The ‘planktonic’ larval stage seen in some marine species of fish refers to the stage in their lifecycle where they are unable to swim and instead drift within the water, thus having little control over their movements and thus rely on the ocean current to provide them with food - meaning they require live feeding within an aquaculture setting
What is metamorphosis within the halibut lifecycle?
Within the early stages of their lifecycle, halibut have one eye on each side of their head however one eye will eventually migrate to the same side at the other eye, a process known as metamorphosis
Why are monosex fish populations sometimes preferred in aquaculture?
Monosex fish populations prevents unwanted breeding
What are the two methods that can be used to achieve a monosex fish population?
Sex reversal
Triploidy
Describe how triploidy can be achieved
Female fry can be treated with testosterone causing them to be genetically female but they produce sperm which can be used to fertilise eggs, resulting in the production of a purely female population. The eggs can then undergo shock treatment to achieve triploidy
What is a flow through production system?
Water is sourced from a clean water source and then pumped in and out of the fish farm system
What is a recirculation production system?
Water is continuously recycled and renewed within the fish farm system
What is this aquaculture production system?
Fish farm cage system
What is this aquaculture production system?
Fish tank system
What is this aquaculture production system?
Fish earth pond system
When is it best to evaluate the health status of your fish?
It is best to evaluate the health status of fish during feeding time as this will be the first indicator of any behavioural changes
What is the main slaughter mechanism used in aquaculture?
Stunning
What are the two bleeding mechanisms used following fish slaughter?
Gill cut
Aortic punture
What can cause vertebral column deformities in fish?
Vertebral column deformities in fish can be caused by a phosphorus deficiency in the early life stages
What can cause jaw deformities in fish?
Jaw deformaties in fish can be caused by a long term phosphorus deficiency
What can cause cataracts in fish?
Cataracts can be caused by a histidine deficiency in fish
Describe an ideal site for a pond
A pond should be in an open space away from trees as trees can contribute to organic material within the pond. A pond should also be on flat ground to reduce debris and harmful material that can be brought in by runoff
How many fish can you have per 1000 litres of water within a pond?
2kg of fish within 1000 litres
What is the minimum recommended volume of water for a freshwater aquaria?
36 litres
What is the recommended water temperature for a marine aquaria?
25°C
What is the recommended water pH for a marine aquaria?
8.3
How often should you carry out maintenance on a freshwater or marine aquaria?
Every 2-3 weeks
What are the five steps of aquaria maintenance?
Check water quality
Remove algae
Clean tank
Carry out a partial water change
Clean filter
What is the primary source of protein within a fish diet?
Fish meal
What is the primary source of lipid within a fish diet?
Fish oil
Which three factors can lead to changes in oxygen levels within a fish habitat?
Temperature
Organic material
Plant activity
How do plants alter the oxygen levels in fish habitats?
Plants will oxygenate the water throughout the day however plants will remove oxygen during the night
What are the three signs of low oxygen levels in fish?
Gasping
Gathering at areas with higher oxygen
Flared gills
Which two factors can increase the CO2 levels in fish habitats?
Respiration
Decomposition of organic matter
List three nitrogenous waste substances which can have adverse effects on fish
Ammonia
Nitrites
Nitrates
Describe briefly the nitrogen cycle within fish tanks
- Ammonia is produced as a by-product of fish metabolism
- Bacteria convert the ammonia into nitrites
- Bacteria convert nitrites into nitrates
- Plants convert nitrates into plant proteins
- Fish eat the plants and convert the plant proteins into animal proteins
Which nitrogenous waste substance can cause methaemoglobinaemia in fish?
Nitrites
Which nitrogenous waste substance can cause promote algae growth in fish habitats?
Nitrates
What is ‘new tank syndrome’?
‘New tank syndrome’ is a condition which can occur in newly established tanks where the tank undergoes a period of instability leading to high levels of ammonia and nitrites
How do you reduce the risk of ‘new tank syndrome’?
Introduce the fish slowly and ensure the filter remains functional
What is ‘gas bubble disease’?
‘Gas bubble disease’ occurs when fish are exposed to high levels of dissolved gas, mainly nitrogen, causing the gas to form bubbles within the fish tissues
List seven ways in which water quality can be improved
Appropriate site selection
Increase water flow rates
Reduce organic material
Increase oxygen
Reduce nitrogenous waste
Reduce temperature
Reduce feeding rate
(T/F) The Animal Welfare Act 2006 does not include fish
FALSE. Fish are vertebrate animals and thus are included in the Animal Welfare Act 2006
