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Disease Management
Health Maintenance and Monitoring
For aquaculture species with mature technologies, the major constraints in production
are usually related to health maintenance, disease occurrence, and product quality.
These issues are inter-related, especially if disease prevention or control implements
have long-term effects on the environment or produce residues that make products
unacceptable for consumption.
Health and Disease
Disease is usually defined as any abnormality of structure or function. This means
that whenever there is something abnormal about the animal, consider it to be a
disease. The level of production can be an indicator of whether an animal is healthy
or diseased.
Ensuring good farm production and animal health starts at the planning stage of
every aquaculture venture. At each step of planning and production, questions and
answers should be anticipated on how to decrease the possibility of pathogen entry
and environmental contamination. These considerations include the following:
- Selection of a production site
- Selection of water source
- Water quality management and control
- Maintenance of various life stages
- Feed quality and feeding practices
- Fish health management
- Proper use of chemicals and veterinary drugs
- Proper sanitation
- Harvesting, holding and transport
- Detailed record keeping
Sources of Infection
Different measures are needed to maintain cleanliness and hygiene within culture
premises, including hatchery, farms, feed etc.
Hatchery Facilities
Maintenance of hygiene in the hatchery can be done simply by disinfecting
with chlorine all facilities (reservoir, larval rearing tanks, algal tanks, rotifer
tanks, Artemia tanks, etc.) and materials (nets, hoses, pails and other
paraphernalia). A well-designed hatchery should have a disposal system for contaminated
effluents to prevent contact with natural bodies of water. If a broodstock facility
is incorporated in the design, this should be separated from larval rearing facilities
since it is well-known that broodstock harbor and transmit various infectious diseases.
Precautionary measures such as provision of footbaths at entrance and exits of production
buildings are effective measures to prevent diseases.
Animals
Any stage of live animals for culture that is brought into new
sites or aquaculture facilities may carry with it associated microorganisms, including
those that cause diseases. Therefore, disinfection and quarantine are carried out
to avoid introduction of new and exotic pathogens.
Natural food
Hatchery technicians should ensure that their phytoplankton and zooplankton cultures
are free of contaminants such as saprophytic protozoans that may become nuisance
during culture. The bacterial populations associated with Brachionus and
Artemia can be checked for harmful and opportunistic pathogens through
microbial culture. Microbial load of natural food can also be reduced by rinsing
them in clean seawater before feeding.
Artificial feeds should be stored properly under refrigeration or in well-ventilated
rooms to avoid rancidity or fungal growth resulting in toxic by-products.
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