Biotechnology and Disease
Resistance in Fish
• Fish in culture are susceptible to a wide
range of bacterial, viral, parasitic and fungal
• Biotechnology can have a direct positive
impact on many of the main elements of fish
• Biotechnology provides powerful tools for the
sustainable development of aquaculture.
• Genetic modification and biotechnology also
holds potential to improve the quality and
quantity of fish reared in aquaculture.
The impact of biotechnology in
Fish health management
• While considerable progress has been made in fish
biotechnology in Asia, the following aspects need to
be further strengthened (Guerrero, 1991):
• Genetic improvement of cultured fish for improved
growth, disease resistance and adaptability to new
farming systems.(i.e. GIFT )
• Production of vaccines and antibodies for the
prevention and control of bacterial and virus
• Development of drugs and other biotechnological
products from marine organisms.
• The stress and disease in intensive fish
culture have led to treatment with antibiotics
and chemicals. regarding the pollution
associated with chemical treatments,
methods such as vaccination and the use of
immunostimulants has developed.
• vaccine must provide long-term protection
against the disease under the intensive
• The primary considerations for any
successful vaccine for aquaculture are cost-
effectiveness and safety.
• Most of the commercial vaccines presently
available consist on inactivated (killed)
• The majority of commercial vaccines are
multivalent and target salmon and trout but
there are expanding opportunities in the
temperate and warm-water species found in
the Asia–Pacific region.
Importance of vaccination
• Vaccines are used to prevent a specific
disease outbreak from occurring and are not
• Its efficiency exists for a longer duration with
one or more treatments.
• No toxic side effects and healthy fish have
better growth performance.
• No accumulation of toxic residues.
• Pathogen will not develop resistance.
• No environmental impact.
VACCINES SPECIES DISEASE
Yersinia ruckeri Bacterin Salmonids red-mouth disease)
Vibrio Salmonids Vibriosis
Koi herpes virus (KHV) Koi carp Koi herpes virus (KHV)
Edwardsiella Catfish Enteric septicaemia
Spring viraemia of carp Common carp Spring viraemia of carp
Biofilm and free-cell Indian major carps Dropsy
Vaccine delivery system
• There are three methods of vaccination in
• 1. Injection delivery system.
• 2. Immersion delivery system.
• 3. Oral delivery system.
• Antibiotics are very useful additions to any
fish-health manager's toolbox, but they are
only tools and not 'magic bullets.‘
• The ability of antibiotics to help eliminate a
fish disease depends on a number of factor
• Antibiotics merely control the population
growth of bacteria in a fish long enough for
its immune system to eliminate them.
• Does the problem actually have a bacterial
• Are the bacteria involved sensitive to the
• Are the proper dosage and treatment
intervals being used?
• Have other contributing stresses been
removed or reduced?
Major Routes of Administration
• Mixed in food
• Bath treatments
List of Antibiotics
• Erythromycin is most effective against
• penicillin, amoxicillin, and ampicillin, are
most effective against gram-positive bacteria.
• Oxytetracycline and related antibiotics are
considered broad-spectrum antibiotics.
• gentamicin, neomycin, kanamycin are very
effective against gram-negative bacteria.
• The sulfa drugs are also considered to be
• Transgenesis may be defined as the introduction of
exogenous gene / DNA into host genome resulting in
its stable maintenance, transmission and expression.
• The technology offers an excellent opportunity for
modifying or improving the genetic traits of
commercially important fishes.
• The first transgenic fish was produced Zhu (1985) in
• To realize the full potential of the transgenic fish
technology in aquaculture, several important
scientific break through are required.
• more efficient technologies for mass gene transfer
• targeted gene transfer technologies such as
embryonic stem cell gene transfer
• suitable promoters to direct the expression of
transgenes at optimal levels during the desired
• identified genes of desireable traits for aquaculture
and other applications
• safety and environmental impacts of transgenic fish.
• Biotechnological research and development
are growing at a very fast rate. The
biotechnology has assumed greatest
importance in recent years in the
development of fisheries, agriculture and
human health.The application of
biotechnology in the fisheries sector is a
relatively recent practice. Neverthless,it is a
promising area to enhance fish production.