health management in aquaculture

197 Pages·2010·2.06 MB·English

HEALTH MANAGEMENT
IN AQUACULTURE
Edited by: GILDA D. LIO-PO, CELIA R. LAVILLA, ERLINDA R. CRUZ-LACIERDA
AQUACULTURE DEPARTMENT
SOUTHEAST ASIAN FISHERIES DEVELOPMENT CENTER
TIGBAUAN, ILOILO, PHILIPPINES
Health Management
in Aquaculture
Edited by
Gilda D. Lio-Po
Celia R. Lavilla
Erlinda R. Cruz-Lacierda
Aquaculture Department
SOUTHEAST ASIAN FISHERIES DEVELOPMENT CENTER
Tigbauan, Iloilo, Philippines
June 2001
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June 2001
ISBN 971 8511 45 8
Copyright © 2001
Aquaculture Department
Southeast Asian Fisheries
Development Center
Tigbauan, Iloilo, Philippines
ALL RIGHTS RESERVED
No part of this publication may be
reproduced or transmitted in any
form or by any means, electronic or
mechanical, including photocopy,
recording or any information storage
or retrieval system, without the permission
in writing from the publisher.
For comments and inquiries:
Training and Information Division
SEAFDEC Aquaculture Department
Tigbauan, Iloilo, Philippines
fax : [phone]
email : [email protected]
[email protected]
website : http://www.seafdec.org.ph
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1 fish kill in a milkfish pen in Pangasinan, northern Philippines
1 2
(PHOTO BY A DE LAVEGA);
3
2 visual inspection of grouper fry in the SEAFDEC hatchery
6 4 (PHOTO BY R BUENDIA);
5 3 examination of a slide under the microscope
(PHOTO BY R BUENDIA);
4 the molecular biology laboratory at SEAFDEC (PHOTO BY R BUENDIA);
5 monitoring of water parameters (PHOTO BY R BUENDIA);
6 shrimp with microsporeans on the abdominal muscle (PHOTO BY R DUREMDEZ)
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The need for specific educational materials on aquaculture relevant to
the tropics has, for several years, been raised in many meetings at-
tended by representatives of state colleges/universities, government
extension offices, and R&D institutions. The need for textbooks be-
came more urgent when a few of the colleges/universities started of-
fering fisheries degree programs through the distance education mode.
SEAFDEC/AQD’s textbook writing project rapidly came into fruition
upon the urging of the Iloilo State College of Fisheries (ISCOF). AQD
has been reputed to house the most number of experts in various
fields of aquaculture, and we are only too glad to share our expertise
and results of decades of research and development.
This textbook on Health Management in Aquaculture is the beginning.
It contains the most up-to-date knowledge of fish and crustacean dis-
eases, the causative organisms, and the measures for disease preven-
tion and control in tropical aquaculture.
Although the primary target reader is the student, there are also other
stakeholders in the aquaculture industry who can use the book for
quick reference - the fish farmers, farm workers and technicians, fish-
ers and women in fishing communities.
To our readers, we urge that you always bear in mind that aquaculture
does not exist in isolation. Aquaculture affects, and, in turn, is af-
fected by its surrounding environment. The responsibility of aquacul-
ture is to increase food supply without damaging the natural support
ecosystems. The issue of fish health in particular is illustrative of this
paradigm. Widespread disease problems can occur only when the cul-
ture environment deteriorates to the point that it favors the growth of
disease-causing organism more than the welfare of cultured species.
Severe economic loss is just one of the consequences.
We hope that this book would contribute immensely to the study of
fish health in aquaculture.
Rolando R. Platon, Ph.D
Chief, SEAFDEC Aquaculture Department
June 2001

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Foreword iii
Preface vii
CHAPTER ONE
Disease development 1
Celia R. Lavilla
How disease develops 2
Disease diagnosis 4
Summary 7
CHAPTER TWO
Viral diseases 9
Gilda D. Lio-Po
Characteristics of virus 9
Major viral infections in fish 11
Major viral infections in penaeid shrimps 16
Prevention of viral infections 21
Summary 22
CHAPTER THREE
Bacterial diseases 25
Eleonor V. Alapide-Tendencia and Leobert D. de la Peña
What are bacteria? 26
Identifying the real cause of a disease; Koch’s Postulates 27
Important bacterial diseases of fish 28
Bacterial diseases of crustaceans 35
Summary 39
CHAPTER FOUR 4444433333
Fungal diseases
Eduardo M. Leaño
What are fungi? 43
Major fungal diseases of fish 45
Major fungal diseases of crustaceans 49
Summary 52
CHAPTER FIVE
Parasitic diseases and pests 55
Erlinda R. Cruz-Lacierda
Common fish diseases caused by parasites 55
Common crustacean diseases caused by parasites 67
Life cycle patterns of fish parasites 70
Summary 72
CHAPTER SIX
Environmental and other non-infectious diseases 75
Gregoria Erazo-Pagador
Fish diseases associated with physico-chemical
properties of water 75
Shrimp diseases associated with physico-chemical
properties of water 77
Diseases associated with physical factors 80
Diagnosis of environmental and other non-infectious diseases 80
CHAPTER SEVEN
Nutritional diseases 83
Celia R. Lavilla
Types of feeds 83
Components of feeds 84
Determining the nutritional status of fish 87
Nutritional deficiency diseases of fish 89
Nutritional diseases of shrimps 90
Feed quality problems with health implications 93
Summary 94
CHAPTER EIGHT
Physical, environmental, and chemical methods of disease prevention
and control 97
Erlinda R. Cruz-Lacierda and Gregoria E. Erazo-Pagador
Physical methods 97
Environmental methods 98
Chemical methods 102
Summary 109
CHAPTER NINE
Immunity and biological methods of disease prevention and
control 111
Jesus Manolo E. Almendras
The fish immune system 112
The crustacean immune system 119
Immunosuppression 123
Biological control 124
CHAPTER TEN
Immunological and molecular biology techniques in disease
diagnosis 137
Leobert D. de la Peña
Immunological techniques 137
Molecular biology techniques 147
Summary 156
CHAPTER ELEVEN
Harmful and toxic algae 159
Romeo D. Caturao 111115555555555
Conditions that stimulate harmful and toxic algal blooms 160
Types of harmful and toxic algal blooms 164
Effects of harmful and toxic algal blooms to fish and marine
environment 167
Strategies in coping with the problem of harmful and toxic
algal blooms 170
GLOSSARY 173
Photo and figure credits 179
INDEX 180
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The preparation of written lectures in training courses at SEAFDEC/AQD was initiated
in 1982. This was spearheaded by Dr. Chua Thia Eng upon implementation of the
Training Course for Senior Aquaculturists in Asia and the Pacific, a collaborative
venture among SEAFDEC/AQD, the Network of Aquaculture Centres in Asia (NACA)
and the University of the Philippines in the Visayas (UPV). Since then, the Fish
Disease course of NACA set the format for the Fish Health Management training
courses at SEAFDEC/AQD that began in 1987. The compiled lecture notes became a
reference for SEAFDEC trainees and the students of local fisheries schools. Thus, in
response to the Iloilo State College of Fisheries (ISCOF) urgent need for a textbook,
the fish health reseachers at SEAFDEC endeavored to modify their written lectures
to textbook standards. Despite existing lecture notes, it took more than a year to
complete.
This is the first textbook on diseases of cultured warmwater fish and shrimps in the
Philippines. Eleven chapters cover essential information on the basic principles of
disease causation, major diseases of cultured fish and crustaceans, particularly
shrimps, and methods of prevention and control. Emphasis is made on major diseases
that occur in the Philippines and other countries in the Asian region. Included also
are topics on harmful algae, immunology and molecular biological diagnostic
techniques. Each chapter begins with a brief preview of its contents, followed by an
in-depth discussion that culminates in a summary. The basic concepts presented
were derived from textbooks on microbiology and fish health published by authors
outside of the Philippines while the scientific information put forth were drawn
from the research and diagnostic findings of the authors, colleagues at SEAFDEC
and other institutions in the Philippines and in other countries. The figures and
photos included were selected from the authors’ collection of disease cases or shared
by colleagues in this field, duly acknowledged at the end of the book. Specific citations
were omitted in the text as students are enjoined to refer to references used for each
chapter. To make the concepts more understandable, a glossary is included. An
index is also part of this textbook for quick location of desired subtopics. Finally,
although laboratory protocols are an essential aspect of fish disease diagnosis, it is
best dealt with separately. Interested readers are referred to published manuals.
Though the authors have strived to make this book learner-friendly, we realize that
a first edition leaves much room for improvement. We, therefore, encourage colleagues
to suggest ways of enchancing the future second edition responsive to the needs not
only of students but those of aquaculturists as well. It is hoped that this textbook
will answer questions on fish health in scientific ways and enhance aquaculturists’
ability to prevent diseases and deal with outbreaks effectively.
Finally, this textbook has become a reality with the support of SEAFDEC/AQD and
its Chief, Dr. Rolando Platon; ISCOF President Dr. Elpidio Locsin Jr; Rene Agbayani,
Pastor Torres Jr, Mila Castaños, Nicanor Primavera Jr, Edgardo Ledesma and Dr.
Evelyn Grace de Jesus.
GD Lio-Po
CR Lavilla
ER Cruz-Lacierda

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Celia R. Lavilla
The need for more and more food fish to feed a growing population gave rise to
aquaculture. Today, aquaculture yields have increased, with more harvests
coming from farms in Asia.
Aquaculture has three phases – the (1) hatchery, (2) nursery and (3) grow-out
phases. Most hatchery operators use tanks to hold the young organisms that
they grow. In the nursery and grow-out phases, tanks, ponds, and floating
cages hold the farmed animals until harvest time.
In aquaculture, any one of three production systems may be used in growing
the chosen species. These are the extensive, semi-intensive, or intensive pro-
duction system. Choice of a system depends on the desired density of animals
to be farmed in a given area. In the intensive system, fish are farmed in high
stocking density. High stocking density results in exposure of the animals to
stress that often leads to disease. Disease outbreaks, in turn, cause production
losses due to lower harvests or aquatic products of poor quality.
Disease is defined as any abnormality in structure or function displayed by
living organisms through a specific or non-specific sign (symptom). Infectious
organisms, wrong management practices and environmental problems can
cause disease in farmed aquatic animals. Tissue or organ damage, reduced
growth rate, or death may indicate disease in fish. The consequence of disease
includes rejection of aquaculture products and the loss of productivity. Persis-
tent disease occurrence might cause the collapse of aquaculture ventures and
threaten the sustainability of the industry as a whole.
Because of their harmful effects, disease and environmental problems have
gained worldwide attention. Although economic losses due to diseases in
aquaculture are difficult to measure, data gathered from the export of various
aquatic commodities may serve as indicators for losses or gains in production.
For example, China’s export figure for farmed shrimp in 1992 was 140,000 met-
ric tons. In 1993, shrimp export went down to only 30,000 metric tons. Viral
disease caused the 79% reduction. Translated to export earnings, the country
lost about a billion dollars from shrimp alone. An ADB/NACA (1991) estimate
of losses in aquaculture due to disease was about US$1.36 billion in 15 Asian
countries in 1990. The situation is even worse at present with viral disease
plaguing shrimp culture facilities worldwide.