Fish Health Management

1
Fish Health Management

• GOALS
• Production of healthy, high quality fish

2
Principles of Health Maintenance

• Maintain conditions which are designed to
  optimize growth, feed conversion, reproduction
  and survival
• Intensive aquaculture
• Enhance natural resistance

3
Maintaining Health

• Inverse relationship between environmental
  quality and disease status of fish
• Changes occur over time (type of system)
• Emphasis of Health management
• Physical features of facility
• Use of genetically improved fish
• SPF stocks
• Environmental control
• Prophylactic/preventative therapy
• Feed quality and quantity

4
Stress

• Adverse situation that affects the well-being of
  individual animals

5
Stress related disease

• Environmental associated
• Microbial diseases
• Decreased resistance to pathogens
• Endemic pathogens

6
Location of site

• Soil, water and fish species must be compatible
• Chose site properly
• Pond aquaculture
• Soil characteristics
• Drainage

7
Avoiding exposure

• Best method to control infectious disease
• Water is effective at delivering pathogens to
  fish (endemic)

8
Avoiding exposure (cont.)

• U.S. Title 50
• Other countries?
• Quarantine
• Isolate stocks for a predetermined period before
  contact with resident fish
• Eradication of Stocks
• Last resort!
• Is it worth it?
• Can you manage around it without introducing
  disease to area

9
Avoiding exposure (cont.)

• Example
• VHSV (1989) Washington
• Destroyed adults that were found to have virus
• Destroyed juveniles
• Great lakes (lake trout) Epidermal
  epitheliotropic disease (herpesvirus)
• Destroyed fish and disinfected contaminated
  facilities
• Appears to have worked
• BKD (Wyoming) (1990)
• Destruction of RBT, lake, CTT, and BrT brood
  stock
• Based on highly sensitive detection technique
  (ELISA)
• No evidence for disease
• Was the cost and consequence greater than the
  value of what was saved?

10
Exposing Dose

• Once pathogen load increases (due to poor
  resistance) DISEASE

11
Extent of contact

• Infection vs Disease?
• Facultative
• Obligate require host to complete life cycle
• Viruses, some bacteria, and few parasites
• Route of transmission
• Carriers

12
Protection through segregation

• Young fish/newly hatched fish
• Fingerlings
• Immunity increasing
• Growout
• Approaching market/release size
• Very resistant to disease
• Can survive in poorest water quality

13
Addition of new fish

• Should take needed precautions when adding new
  fish to existing stocks
• Home aquaria or large facilities

14
Breeding and Culling

• Important in the development of domesticated
  stocks that perform well
• Improve by selecting for desired traits
• Future possibilities (genetic engineering)
• Gene manipulation
• Hybridization/transgenic

15
Eradication/prevention/control

• Eradication
• Prevention
• Control Reduction of problem to an
  economically/biologically manageable level

16
Anticipating problems

• Good health records for each pond
• Water quality/quantity
• Stay on top of things!!

17
Fish Health Monitoring

• Early diagnosis
• Know what normal is!

18
Question?

• You are in charge of fish health monitoring at an
  aquaculture facility.
• During morning rounds you notice that a first use
  pond containing RBT (50g/fish) is having some
  problems. Fish appear lethargic, and some dark
  fish are observed.
• What possible problems may be causing this?
• How would you narrow the possibilities down?
• You suspect the problem to be disease related,
  what would you do?