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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.