Disease Resistance in Fish
• Fish in culture are susceptible to a wide
range of bacterial, viral, parasitic and
• Biotechnology can have a direct positive
impact on many of the main elements of
fish health management
• Biotechnology provides powerful tools for
the sustainable development of
• 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
Genetic improvement of cultured fish for improved
growth, disease resistance and adaptability to new
farming systems.(i.e GIFT )
. Production of vaccines and monoclonal 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
inactivated (killed) disease agents
• 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
Importance of vaccination
• Vaccines are used to prevent a specific
disease outbreak from occurring and are not
• á Its efficiency exists for a longer
duration with one or more treatments.
• á No toxic side effects and healthy fish
have better growth performance.
• á No accumulation of toxic residues
• á Pathogen will not develop resistance.
• á Theoretically it can control any
bacterial and viral disease.
• á No environmental impact.
VACCINES SPECIES DISEASE
Yersinia ruckeri Bacterin Salmonids red-mouth disease)
Vibrio salmonicida Bacterin Salmonids Vibriosis
Koi herpes virus (KHV) Koi carp Koi herpes virus (KHV) disease
Edwardsiella ictaluri Bacterin Catfish Enteric septicaemia
Spring viraemia of carp virus Common carp Spring viraemia of carp
Biofilm and free-cell vaccines Indian major carps Dropsy
Use of Antibiotics
• Antibiotics are very useful additions
to any fish-health manager's toolbox,
but they are only tools and not
• 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.
• 1) Does the problem actually have a
• 2) Are the bacteria involved sensitive
to the antibiotic chosen?
• 3) Are the proper dosage and
treatment intervals being used?
• 4) Have other contributing stresses
been removed or reduced?
Major Routes of
• Mixed in food
• Bath treatments
List of Antibiotics
• Erythromycin is most effective against
• including penicillin, amoxicillin, and
ampicillin, are most effective against gram-
• 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
transgenics may be defined as the introduction of
exogenous gene / DNA into host genome resulting
in its stable maintenance, transmission and
The technology offers an excellent opportunity for
modifying or improving the genetic traits of
commercially important fishers
The first transgenic fish was produced Zhu et al.
(1985) in China,
To realize the full potential of the transgenic fish
technology in aquaculture, several important
scientific break Ð through are required.
• There include
• more efficient technologies for mass gene
transfer (ii) targeted gene transfer
technologies such as embryonic stem cell
gene transfer (iii) suitable promoters to
direct the expression of transgenes at
optimal levels during the desired
developmental stages (iv) identified genes
of desireable traits for aquaculture and
other applications (v) informations on the
physiological, nutritional, immunological
and environmental factors that maximize
the performance of the transgenics of the
transgenics and (vi) 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.