Bell Work

1
Bell Work

• What are the 5 stages of fish development ?

2
Identifying Diseases and Parasites of Fish

• Area Animal Science
• Unit Aquaculture
• Lesson 4

3
Objectives

• Describe the common pathogens that affect fish.
• Identify common methods of preventing pathogens
  from infecting fish.
• Create a method of keeping fish pathogen free.

4
What is a Pathogen?

• A pathogen is an organism that causes disease in
  a fish.
• If conditions are good fish rarely experience a
  serious outbreak of disease.
• If conditions permit, an outbreak can be
  devastating.

5
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 fish under
  stress and weakens their ability to resist
  infection.
• Cold water, poor water quality, and poor
  nutrition.

6
3rd Condition

• Pathogenic Organisms
• Must be an organism present in the water that
  needs a host to infect.

7
What types of organisms cause disease?

• 4 organisms that can cause disease
• Parasites,
• Bacteria,
• Viruses,
• Fungi.

8
How do Parasites affect fish?

• Parasites are organisms that grow, feed, and is
  dependant on its host while not contributing to
  the host's benefit.
• Worms
• Protozoa
• Fish Lice

9
What are Bacteria?

• Single-celled organisms.
• Once the get into a fish's system, they can
  reproduce quickly and can be extremely
  contagious.
• Under good conditions fish have several natural
  defenses
• The most important is the slime coat.

10
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 in an
  aquaculture system can be devastating to the
  system.

11
How do Fungi affect fish?

• Probably the most unique organism in fish
  pathology.
• Can be as small as a single-cell or cover an
  enormous area.
• Affect specialized areas in fish and can cause
  disease.
• Most vulnerable are eggs and young fry.

12
What are some stressful conditions to fish?

• 2 conditions that can cause stress to fish
• Environmental
• Nutritional

13
Environmental Stress

• 3 types
• Acute
• Some part of the environment is outside the
  fish's tolerance 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 stress
  factor.

14
Nutritional Stress

• Nutrition is important in fish.
• In natural conditions fish can usually find
  enough food to properly nourish themselves.
• In intense operations it is important that fish
  have proper nutrition
• They become subject to chronic stress.

15
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 spread of
  the disease.
• In recirculating systems it is of the utmost
  importance to treat the disease as fast as
  possible in order to prevent it from spreading.