Fish and shellfish

1. Disease control through
environmental management in fish

2. Introduction
• Providing water sources free of pathogens.
• Protection from the transfer of pathogens.
• Disinfection of ponds, fish culture units and
equipment; winter freezing and summer
drying of ponds. ...
• Optimalization of environmental conditions.

3. Characterstics
• Diseases pose a major threat to aquaculture.
A loss to the tune of 10-15% of production
cost may be incurred due to disease problems.
Hence, it is essential to take care of ponds and
hatcheries to prevent the disease spread.

4. • Mortality in fish often is noticed due to poor
management of ponds and hatcheries. The
pond environment, particularly the water
quality in ponds and hatcheries play crucial
role in causing mortality and triggering
infection.

5. • Ponds need to be limed and fertilized at regular
intervals to maintain optimum water quality and
load of fish food organisms. The common
management problems that lead to mass or large
scale mortality in farms and their preventive
measures are given hereunder. Further, the fish
farmers are advised to contact fish health experts
once any disease signs are noticed in a pond or
mortality recorded, if any, to prevent further
spread of infection to nearby ponds.

6. Do's and Don'ts
• Maintain optimum water quality.
• Proper liming and fertilization.
• Additional liming is beneficial in terms of
disinfecting pond environment .
• Proper stocking density and Provision of
balanced feed.
• Proper stocking density Ø Provision of
balanced feed.

7. Cont…
• Avoid foul smell in pond water Ø Remove
unwanted fish and snails.
• Stock the ponds when the water quality is
good and pond having adequate fish food
organisms Ø Remove the infected or diseased
fish during sampling and bring it to the notice
of fish health workers.

8. Cont…
• Use good quality water in hatcheries .
• Remove aquatic weeds, and avoid blooms
• Use always sun-dried nets before sampling
• Don't use same net or equipments after being
used in infected ponds.
• Avoid entry of birds, dogs and other fish eating
animals to pond premises Ø Use bamboo poles to
look for laying of ectoparasite eggs to undertake
immediate treatment, if noticed Ø Dry the weeds,
snails after removal from one pond

9. • Avoid entry of birds, dogs and other fish
eating animals to pond premises.
• Use bamboo poles to look for laying of
ectoparasite eggs to undertake immediate
treatment, if noticed.
• Dry the weeds, snails after removal from one
pond.
• Avoid plant leaves falling into the ponds .

10. SANITARY AND PHYTOSANITARY (SPS)
AGREEMENT
• The Agreement on the Application of Sanitary
and Phytosanitary Measures (SPS Agreement)
is one of the multilateral trade agreements,
which all members of the World Trade
Organization (WTO) are committed to
observe.

11. • As the membership of the WTO grows, the
principles embodied in the SPS Agreement are
becoming de facto international rules
governing the domestic and foreign trade of
foods, feeds and other agricultural
commodities.

12. • The compliance with the obligations of the
SPS Agreement as well as the exercise of rights
accorded by the Agreement are a key to
ensuring food safety and animal and plant
health in all countries, while promoting free
trade and development.

13. OVERVIEW OF THE SPS AGREEMENT
• The SPS Agreement covers food safety, animal life and
health as well as plant life and health, in accordance
with its scope and objectives found in the Preamble
and Article 1. The Article 2 sets out basic rights and
obligations of WTO members with regard to sanitary
and phytosanitary measures: these measures should
be applied only to the extent necessary; measures
should be based on scientific principles and not
maintained without sufficient scientific evidence; and
no arbitrary or unjustified discrimination is allowed,
etc. Below are some of the principal provisions of the
Agreement.

14. Harmonization
• The Article 3 of the SPS Agreement
encourages WTO members to harmonize their
national measures with standards, guidelines
and recommendations .The Office
International des Epizooties (OIE) are
recognized under the SPS Agreement as
international benchmarks within the fields of
food safety, plant life and health and animal
life and health, respectively guidelines and
recommendations.

15. Equivalence
• The Article 4 of the SPS Agreement
emphasizes the notion of equivalence. WTO
members have to accept different measures
providing the same level of health protection
against risks of disease or contamination, even
if they are less sophisticated than those used
by them.

16. Cont…
• Steps to be taken to promote recognition of
equivalence have been identified in “Decision
on the Implementation of Article 4 of the
Agreement on the Application of Sanitary and
Phytosanitary Measures” (G/SPS/19), effective
on 24 October 2001.

17. Risk Assessment
• The Article 5 of the SPS Agreement
underscores the importance of risk
assessment as the scientific basis for sanitary
and phytosanitary measures. It also identifies
factors that need to be taken into account
when determining the member’s appropriate
level of protection (ALOP) from sanitary and
phytosanitary risks.

18. Adaptation to Regional Conditions
• The Article 6 of the SPS Agreement requires a
WTO member’s sanitary and phytosanitary
measures to be adapted to the characteristics
of the area from which the product originated
and to which the product is destined and they
should be recognize pest- or disease-free
areas as well as areas of low pest or disease
prevalence.

19. Vaccines used in aquaculture
• The process of stimulating protective immune
responses in fish against pathogenic
microorganisms by exposing them to non-
pathogenic forms or components of
microorganisms is referred to as vaccination.

20. Cont…
• Aquaculture has been globally recognized as
the fastest growing food production sector
(FAO). The intensive farming of finfishes and
shellfishes has led to an imbalance of optimal
culture conditions, which shows increased
susceptibility to infectious disease. The first
report on fish vaccination was by David C. B.
Duff and he is regarded as "Father of fish
vaccination".

21. Characteristics of vaccine
• The vaccine used should be safe and should not
cause toxicity
• . The vaccine should have high immunogenicity.
• The vaccine should protect the animal for a
longer period. In fish, duration of one year or life
long protection can be said to be commercially
effective for a vaccine preparation. The vaccine
should be specific against a particular pathogen.
It should not protect or favour the other
pathogens.

22. There are three methods of
vaccination in fish
• Injection of delivery system.
• Immersion of delivery system.
• Oral delivery system.

23. Injection delivery system
• Injection delivery system is an effective way of
inducing antibody response in fish. The
injection may be intraperitoneal or
intramuscular. But the major setbacks are, it is
time consuming, labour intensive and
consequently expensive to administer to large
number of animals.

24. • During the course of injection, handling stress
affects their ability to produce optimal
immune response.

25. Immersion delivery system
• Immersion delivery system of vaccines is a
potential commercial process. It is a
hyperosmotic immersion technique, where
prior to immersion in antigen solution fish are
dipped for a short time in a hyperosmotic salt
solution which enhances the uptake of
antigen. The advantages are, large number of
fish can be vaccinated at the same time and it
can be used to vaccinate fry of any size above
the critical size of immune responsiveness.

26. Cont…
• The main disadvantage of this method is the
fish is subjected to stress. Spray vaccination is
a variant of direct immersion where antigen in
sprayed under pressure on to the fish, as they
are propelled along a shallow channel.

27. Oral delivery system
• Oral delivery system through feed is a
potentially useful method of vaccination.
• This method do not cause stress to the fish. It
can be used to vaccinate the fish of any size
and requires no extra time or labour than
normal farm husbandry.

28. Cont…
• The main limitations of this method are, to
obtain effective immunity it is necessary to
give a large dose of antigen (i.e.) the total
amount of antigen needed is much more
higher than injection and immersion delivery
systems and the immunity which the oral
delivery system provokes is poor and not as
long lasting as injection delivery system.

29. Immuno-stimulants used in
aquaculture.
• Immunostimulants activate the immune
system of aquatic animals and enhance their
capacity for disease resistance. Cellular and
humoral immunity constitute the specific
immune systems of fish.

30. Cont…
• The use of immunostimulants in equine
medicine is promoted for the preventive or
adjunctive therapy of respiratory diseases and
other infectious diseases, acquired
immunosuppression secondary to stress
(transportation, training, weaning),
immunosuppressive treatment, infiltrative
diseases, metabolic/endocrine diseases.