4 disease in fish
TRANSCRIPT
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Bell Work
What are the 5
stages of fish
development ?
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Identifying Diseases and
Parasites of Fish
Area: Animal Science
Unit: Aquaculture
Lesson 4
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Objectives
Describe the common pathogensthat affect fish.
Identify common methods ofpreventing pathogens frominfecting fish.
Create a method of keeping fishpathogen free.
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What is a Pathogen?
A pathogen is an organism thatcauses disease in a fish.
If conditions are good fish rarely
experience a serious outbreak ofdisease.
If conditions permit, an outbreak can
be devastating.
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What are some conditions
necessary for disease to occur? 3 things must be present:Susceptible Host-
Must be a host that has been weakened
for some reason or another
Stressful Condition-
Must be a condition which puts a fishunder stress and weakens their ability toresist infection.
Cold water, poor water quality, and poornutrition.
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3rd
Condition
Pathogenic Organisms
Must be an organism present in thewater that needs a host to infect.
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What types of organisms
cause disease?
4 organisms that can cause
diseaseParasites,
Bacteria,
Viruses,
Fungi.
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How do Parasites affect
fish? Parasites are organisms that grow,
feed, and is dependant on its hostwhile not contributing to the host's
benefit.
WormsProtozoa
Fish Lice
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What are Bacteria? Single-celled organisms.
Once the get into a fish's system, they
can reproduce quickly and can beextremely contagious.
Under good conditions fish have
several natural defensesThe most important is the slime coat.
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How do Viruses harm fish? Microscopic parasites.
Invade living cells of their host in order to
reproduce. Use the genetic makeup of the cell to
reproduce and can cause extreme damage
to a fish.
Have no known cures and an outbreak inan aquaculture system can be
devastating to the system.
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How do Fungi affect fish? Probably the most unique
organism in fish pathology.
Can be as small as a single-cell orcover an enormous area.
Affect specialized areas in fish and
can cause disease. Most vulnerable are eggs and
young fry.
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What are some stressful
conditions to fish?
2 conditions that can cause
stress to fish:Environmental
Nutritional
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Environmental Stress
3 types: Acute
Some part of the environment is outside the fish'stolerance range.
Ammonia levels and O2 levels.
Shock- Fish experience rapid changes in an environment.
Sudden change of temperature.
Chronic- Long term exposure to poor environmental quality.
Probably the most common environmental stressfactor.
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Nutritional Stress Nutrition is important in fish.
In natural conditions fish can usuallyfind enough food to properly nourishthemselves.
In intense operations it is important
that fish have proper nutrition They become subject to chronic
stress.
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How to prevent disease. Keep conditions for the fish at optimal
levels.
Important to
keep water clean and oxygenated,
temperature at the proper levels, providing quality feed.
If disease is recognized:
Treatments should be done to prevent spreadof the disease.
In recirculating systems it is of the utmostimportance to treat the disease as fast aspossible in order to prevent it from spreading.