Field Document 2
ESTABLISHING DIAGNOSTIC WORK AND RESEARCH ON FISH DISEASES AND FISH HEALTH MONITORING AT FARTC (CIFRI), DHAULI
Table Of Contents
A report prepared for the
Intensification of Freshwater Fish Culture and Training Project
Fish Health Protection and Diseases Consultant
This is one of a series of reports prepared during the course of the UNDP/FAO project identified on the title page. The conclusions and recommendations given in the report are those considered appropriate at the time of its preparation. They may be modified in the light of further knowledge gained at subsequent stages of the project.
The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the United Nations or the Food and Agriculture Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.
The intensification and further development of freshwater aquaculture in India urgently requires knowledge, research facilities and research and expertise on fish diseases and fish health protection.
This report describes the initiation of work in this area at the Freshwater Aquaculture Research and Training Centre of the Central Inland Fisheries Research Institute, as part of the FAO/UNDP Project IND/75/031.
Work accomplished in theoretical and practical training of young scientists on fish diseases and research methodologies, as well as assistance in establishing adequate conditions for research are described. During the practical training three fish diseases were diagnosed that had so far not been reported in India. In a pond experiment set up for training, the efficiency of antibiotic administration during handling in preventing post-handling losses due to columnaris disease was clearly demonstrated.
Considering the present and future needs for research on fish diseases and health protection and the probable role of FARTC in it, proposals on organization of work in this area were prepared. It is suggested that the research team work as the Unit for Ichthyopathology and Fish Health Protection. The Unit should cooperate closely with other research teams and scientists at FARTC. Fields of work in the Unit and proposals for five initial 3 year research programmes are outlined. The research projects are oriented towards development of methodologies for detection, identification and the inventory of diseases in composite fish culture.
The Food and Agriculture Organization is greatly indebted to the following organizations and individuals who assisted in the implementation of the project by providing information, advice and facilities:
Dr V.R.P. Sinha, National Project Director; Dr A.V. Natarajan, Director of CIFRI, and Orissa University of Agriculture and Technology, especially Dr J.N. Mohanty, Dr B.C. Nayak, Dr S.N. Panda and Dr N.K. Dutta of the Veterinary School.
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.
This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.
1.1 Terms of Reference
1.2 Background Information
2. SUMMARIZED DESCRIPTION OF WORK
2.1.1 Theoretical Background
2.1.2 Practical Training
2.1.3 Organization of the Seminar on Fish Health Protection
2.1.4 Other Activities
2.2 Aid in Establishing Adequate Conditions for Research
2.2.1 Utilization Space
2.2.2 Installation of Equipment
2.2.3 Other Activities
3. RESULTS OBTAINED DURING PRACTICAL TRAINING
3.1 Laboratory Work
3.1.1 Diagnostic Work
3.1.2 Fish Cell Cultures
3.2 Pond Experiments
4. PROPOSALS FOR ORGANIZATION OF WORK
4.2 Unit for Ichthyopathology and Fish Health Protection
4.2.1 Research Fields for Future Planning
4.2.2 General Diagnostic Work
4.2.8 Collection of Specimens, Pathogens and Slides
5. AID IN SETTING UP RESEARCH PROJECTS
5.1 Fish Health Monitoring in Composite Fish Culture
5.1.1 Scientists To Work on the Project
5.1.3 Practical Utility
5.1.4 Technical Programme
5.1.5 Duration of the Programme
5.2 Preparation and Use of Primary Cell Cultures from Indian Major Carps and of Cell Lines for Virology
5.2.1 Scientists To Work on the Project
5.2.3 Practical Utility
5.2.4 Technical Programme
5.2.5 Duration of Project
5.3 Development of Methods for Isolation, Identification and Maintenance of Bacterial Pathogens in Indian Major Carps
5.3.1 Scientists To Work on the Project
5.3.3 Practical Utility
5.3.4 Technical Programme
5.4 Development of Methodologies for Detection and Identification of Diseases Caused by Parasites
5.4.1 Scientists To Work on the Project
5.4.3 Practical Utility
5.4.4 Technical Programme
5.4.5 Duration of the Project is Three Years
5.5 Histopathological Methods for Study of Kidney and Liver Pathology in Indian Major Carps
5.5.1 Scientists To Work on the Project
5.5.3 Practical Utility
5.5.4 Technical Programme
5.5.5 Duration of the Project is Three Years
Appendix 1: PROGRAMME OF SEMINAR ON FISH HEALTH PROTECTION AT THE KVK AND TRAINERS' TRAINING CENTRE
The Government of India, assisted by the United Nations Development Programme and the Food and Agriculture Organization of the United Nations, are engaged in the intensification of Freshwater Fish Culture and Training Project (FI:DP/IND/75/031).
As part of the operation of the project, FAO assigned Dr N. Fijan as Fish Health Protection and Diseases Consultant from 12 October 1980 to 11 January 1981, with the following terms of reference:
to assist in developing the laboratory diagnostic methods for viral, bacterial, parasitic and other diseases and to initiate research programmes on fish health and diseases, and
to assist in developing the fish health monitoring system.
This report describes the work carried out by the consultant under the above terms of reference. In addition it contains proposals for long and short term approaches to laboratory diagnostic work and research on fish diseases, as well as on fish health monitoring at the Freshwater Aquaculture Research and Training Centre (FARTC), Dhauli.
Research at the Central Inland Fisheries Research Institute (CIFRI) on composite fish culture and implementation of results in field trials all over India have shown that intensive pond fish culture technology can secure very high yields (over 7 000 kg/ha) in this country.
From the worldwide experiences it is known that fish diseases represent a major threat to fish culture in general and especially to intensive biotechnologies. The personal contacts of the consultant with fish culture scientists revealed the presence of an experience or an opinion among some of them that, up to now, fish diseases do not seem to have a significant impact on composite fish culture in India, as managed by methods developed so far. According to these opinions, losses in ponds can be avoided by already known methods in technology, including prevention of predation and of some parasitic invasions of skin and gills. On the other hand, some reports indicate that diseases do occur and have an impact on production in polyculture ponds. These reports as well as the limited laboratory diagnostic work and an experiment conducted at FARTC during the consultancy indicate that pond fish culture in India already stands at the same risks from diseases as the aquaculture in other countries.
Some information is available on fish diseases and their control in India. There are also some data on zoological aspects of fish parasites, on seasonal incidence of some ectoparasites and on gross symptoms of some diseases noted in composite fish culture. Generally, however, there is a lack of well documented research on most etiological groups of diseases and treatments for them. Bacterial and viral diseases were generally not a subject of up to date research by adequate laboratory methodologies. Fish health monitoring is performed only to a limited extent at the field level. This situation indicates a serious lag in data on diseases and their prevention behind the research and practical results on fish production in ponds. In contrast to the situation in developed countries and in some developing countries, India does not yet have a diagnostic institution or laboratory for fish diseases. The Project IND/75/031 has therefore included work on fish diseases as one of its main objectives.
The FARTC at Dhauli is the first location in India that will have facilities and personnel for research and diagnostic work on all major groups of fish diseases and work on health monitoring in aquaculture. In order to fulfil its future role in the development of this field in India and in countries of this part of world that do not yet have such facilities, the initial planning of work on fish diseases is of utmost importance and can have far reaching consequences. The consultant has therefore included in this report general recommendations on organization of the work and on possible future plans.
The consultant stayed at FARTC, Dhauli, from 16 October 1980 to 6 January 1981. The stay was prolonged for a dew days upon the request of the project director in order to complete some experiments. A four day break in above stay was made from 27 to 30 December for a visit to Barrackpore on the request of the Director of CIFRI. There the consultant informed the director about the progress in his work at FARTC. He also went to two research stations of CIFRI to investigate two fish disease problems and to advise the research workers about possible research approaches for solving the etiology of these diseases.
Four young FARTC scientists R.K. Dey, D. Kumar, B.K. Mishra, K. Suresh) were assigned for work in this field. In addition, two CIFRI scientists (R.N. Pal and D.M. Swami) worked with the group for about one month each.
The work of FARTC staff scientists could be started only after adequate training. The programme of training was adjusted to the fact that none of four assigned FARTC scientists had sufficient previous knowledge of fish diseases, fish health monitoring and protection. Special emphasis was placed on topics that are not fully covered in existing English or other literature, and on practical training.
The following topics were covered during the training:
This was carried out on the following topics:
Upon completion of the training by the consultant on general aspects of fish diseases, seven scientists gave a seminar for participants in the ongoing course at the KVK and Trainers' Training Centre of CIFRI. The purpose of this seminar was twofold: (i) to give an opportunity to the scientists that were trained by the consultant to confirm and deepen their knowledge, and (ii) to provide trainees at the Centre with basic knowledge in this field and to initiate cooperation in fish health monitoring between field workers and the FARTC researchers. The programme of the seminar is attached as Appendix 1.
The consultant gave three lectures on fish diseases and health protection. In all three instances fruitful discussions developed, showing great interest in this field and its importance. Lectures were held for (i) Director and Extension Officers of the Department of Fisheries, Government of Orissa, (ii) staff members and students of the Veterinary School at the Orissa University of Agriculture and Technology, and (iii) scientists of CIFRI at Barrackpore. The lecture under (i) was of special importance for the development of cooperation in work on fish diseases and health protection between FARTC and the Department of Fisheries.
Four laboratories and one storage room were allocated by the project director for work on fish diseases and health protection. The first laboratory will serve as the room for dissection and general examination of incoming fish samples, as well as for work on diseases caused by parasites. The second laboratory will accommodate work on histopathology and on bacterial diseases. The third room will be the laboratory for cell culture and virology. The fourth room will serve as the wet laboratory for experiments with fish in aquariums and provide space for washing and sterilization of glassware. Depending on developments in the research and on practical factors, the space may have to be enlarged in the future.
The consultant made recommendations for setting up the sterile chamber for cell culture and virology work, needed adaptations of furniture and suggested plans for setting up the wet laboratory.
Together with the local staff, the consultant installed the equipment that came to FARTC from the Cuttack Station of CIFRI. When this equipment arrived, it was found that it did not function properly and a claim was sent to the supplier.
In order to secure information about availability of commonly used medicines, the consultant requested and obtained information and literature from several pharmaceutical companies in India. Collection of such information will be continued by staff to have on hand broad information about locally available drugs for research and field use and their prices.
To facilitate the diagnostic and research work, the consultant prepared up to date flow charts for isolation and identification of fish pathogenic viruses and bacteria. The charts were to be prepared as wall posters.
The consultant also discussed with and advised the FARTC staff and the potential producers about the design of experimental aquaria, troughs and tanks that will be procured by FARTC for research purposes.
Cooperation of scientists assigned to work with the consultant and other researchers and research groups was initiated. On one hand, diagnostic information and preventive treatment recommendations were given for experimental fish. On the other hand, advice and cooperation was utilized or planned with economists, nutritionists, water chemists and statisticians.
During the consultant's stay in Dhauli, 101 fish were dissected and their organs examined microscopically. Material for bacteriological examination was taken from 28 fish, for parasitological examination from 10 specimens and for histopathological examination from 35 fish. In addition to pathoanatomical diagnoses, tentative bacteriological diagnosis was set up for 20 fish, final histopathological diagnosis in 4 fish and parasitological diagnosis in 82 fish. Materials under processing and isolated strains of bacteria will be used for setting up final diagnoses and for research purposes.
Examined according to species were 66 rohu, 10 catla, 7 mrigal, 3 common carp and 15 silver carp.
Of the above fish, 66 originated from ponds at FARTC, 27 from nearby village ponds, 5 from the Trainers' Training Centre ponds, and 3 from the Cuttack hatchery. Another break-down from the records shows that 76 of these fish were examined directly after netting from ponds. Two of them had malformations, while the others did not show external signs of disease. There were 25 fish brought for examination from laboratory experiments set up by groups of scientists working on nutrition and on genetics or from the pond experiment set by the fish disease group.
The most striking finding was that 100 percent of the rohu examined suffered from severe pathological changes in their kidneys, detectable only by microscopic examination. Changes seemed to be more pronounced and rather severe in two year fish. They are sufocate to chronic. Findings were confirmed by histopathological examination. Fish had necrotic and degenerative changes in most of tubules (nephrosis) and focal accumulation of a yellowfish material, which was sometimes surrounded by a weak chronic connective tissue encapsulation. The yellowfish micronodules were less abundantly present in liver and in one case very abundantly in ovaries. In most of these fishes, myxosporidian specks were detected in kidneys. It is difficult to give an opinion now whether there is a causal or any relationship between the myxosporidian parasite, the nodules and the nephrosis. Since such a 100 percent rate of heavy kidney damage, as well as the occasional damage of other organs, definitely must have an influence on the condition, growth rate and food utilization of the affected rohu, this problem requires thorough further investigation.
The second important finding in the laboratory was that, after netting and handling (material available so far was limited only to fish in experiments), rohu and common carp suffer from symptoms and mortality typical of the columnaris disease. A Flexibacter columnaris-like myxobacterium was isolated in pure culture from kidneys of several affected specimens and was abundantly present in skin lesions. This problem is of known significance in warmwater pond culture of North America and Europe. The disease can affect almost all fishes but there are some variations in species susceptibility. In some species it occurs almost regularly after netting and stocking. It also develops spontaneously in open waters and ponds, often affecting only gills. The findings here indicate that, in all cultivated species, prevention of this disease may have practical significance for reducing losses after netting, handling and stocking operations. Research in this field is urgently needed.
A possibly significant problem was detected by diagnosing enteritis in mrigal and the finding of the intestinal protozoan parasite from the germs opalina, which has not been reported in fishes from temperate zones. Further work on fish health monitoring should indicate the incidence and importance of this condition and the role of this parasite in it.
Presence of yellow clusters of cyst-like units in the intestinal content of some fish, which could eventually be spores of evecidian parasites, also requires further monitoring and investigation.
It can be concluded that health monitoring in ponds and diagnostic work on fish disease cases in India can provide more than ample material for research on fish diseases and their prevention, thus opening possibilities for incorporation of better health protection measures in aquaculture for higher and more economic yields.
These are the essential prerequisite for diagnostic and research work on viral fish diseases: preparing and maintaining of cell cultures requires a special laboratory environment, washing and preparation of glassware, media and other supplies, as well as the application of a technique that is sophisticated for the newcomer to this field. At the end of the consultant's assignment, only improvized conditions for this work could be secured. One attempt to prepare primary cell cultures from rohu could be made and partial success had been achieved. The continuation of this research work and early securing of prerequisites for proper methodology are essential for progress in research and diagnosis of viral diseases.
During the consultant's assignment one pond experiment was completed and the second one started.
In addition to training, the aim of the first experiment was to determine the influence of poor fish handling on losses and the possibility of preventing them by use of antibiotics.
The experiment was carried out in 12 ponds that were randomly used for four experimental treatments of rohu (650 g). Two stocking densities were used. Six ponds (two densities) were stocked with fish that received penicillin plus streptomycin intraperitoneally, while fish for the other six ponds received sham-injections of distilled water. All fish were treated equally otherwise. Their allocation to groups was also randomized. The experiment lasted 12 days. Mortalities occurred 2 to 5 days after stocking and then ceased. All sick and dead fish exhibited symptoms of columnaris disease, while some also had saprolegnia infection of the skin. Flexibacter columnaris was isolated from skin lesions and kidneys of sick and dead fish.
Mortality in fish that received the antibiotics by injection was 1.75 percent and the mortality in non-antibiotic-treated group was 27.18 percent. The stocking density did not affect the mortality rate.
The above experiment indicates that an outbreak of columnaris disease can be triggered in rohu by handling. This is a known fact in fish culture of warmwater species in Europe and North America. The results obtained suggest that injection of suitable antibiotics can decrease losses after handling of broodstock during spawning operations, and that further experiments are needed to assess losses during normal stocking of ponds due to handling, as well as on prevention of such losses by bath or oral treatment of fish prior to stocking.
The second experiment was planned to find out if treatment with a nitraofuran compound can reduce the myxosporidiosis and kidney damage in rohu.
The health of cultivated fish can be adversely affected by numerous biotic and abiotic factors. The number of these factors in fish medicine is even larger than in human or veterinary medicine. Research on fish diseases and fish health protection encompasses, therefore, a constantly increasing number of narrow research fields. As in other research areas, development of sciences and their methodologies now leaves very little space for encyclopaedic oriented type of investigations. Bearing in mind that research on fish diseases has first to gain more ground in India and that practically oriented work must have priority, only a few not quite so narrow fields can be covered at present.
All young scientists starting to work on ichtyopathology and health protection at FARTC should develop knowledge and research techniques on general problems and prevention of diseases. In addition to this, each of them should concentrate on work in one field, according to specific research techniques.
In the first period of research development, general examination techniques for fish, basic bacteriological, parasitological, virological and histopathological techniques, as well as experimentation on prevention and treatments of diseases, should be mastered and used in diagnostic and research work.
Scientists assigned to these fields should work as a homogeneous team, supplementing each other's activity. This is essential for avoiding situations occurring sometimes in some countries with narrow specialists, where the same fish mortality may be attributed to quite different diseases by different researchers, thus confusing the fish farmer or the institution seeking advice for prevention or treatment of diseases.
For the development of working fields it is essential that a significant part of the activity be devoted to diagnostic examination of fish from as many ponds as possible from a large territory. Such activity can be secured through research programmes on health monitoring and taking inventory of disease problems in pond culture. This work is an essential prerequisite for proper selection of research priorities in ichthyopathology, as well as in fields of prevention and treatment. On the basis of diagnostic findings, research can be oriented towards the most urgent needs of aquacultural practice.
Within the diagnostic work, every effort should be made to ensure that fast and reliable diagnostics, together with proper recommendations for disease prevention and treatment reach the fish farmers or owners of the fish as soon as possible. Proper organization of work and development of appropriate methodology are needed for such performance.
For reasons mentioned in 4.1 above and in order to comply with proposed plans on research approaches and responsibilities at FARTC as the Regional Lead Centre for the project RAS/76/003, the consultant suggests that the four scientists assigned to the work on fish diseases start to function as the Unit for Ichthyopathology and Fish Health Protection. Training and utilization of assigned space has been carried out with this proposal in mind.
Full coverage of fish health problems will be of growing importance for development of aquaculture in India. It is useful therefore to foresee all main research fields which will have to be developed either immediately or at a later stage. These fields may be listed as follows:
The list may be useful for long-term planning of personnel, space, facilities, training and equipment.
Programmes covering some aspects of fields listed as i, ii, v, x and xi should be initiated immediately, as suggested in subsequent paragraphs of this section and in section 5.
This basic work should be performed by all four scientists of the unit and should consist of activities described below.
Selecting, packing and transporting fish samples from ponds to laboratory, checking main water quality parameters on the spot and taking water samples. Accepting samples of cultivated carps and taking case histories from extension service personnel, state fisheries department, farmers or staff members of FARTC. Recording arrivals of samples at the laboratory. Keeping records on case histories, findings, diagnosis and recommendations. Preparing annual report on diagnosed cases.
Storage of live or dead fish samples in aquarium, refrigerator or freezer if necessary.
Clinical examination, dissection, macroscopic and microscopic examination of effected and suspect organs and tissues; taking of material for hematological, histopathological, parasitological, bacteriological, mycological, virological and other examinations, as well as for biological experiments (transmission of disease, if necessary for diagnosis).
After pathoanatomical diagnosis and collecting data on results of other examinations, setting up of final diagnosis. Quick reporting of final diagnosis and recommendations for prevention and treatment to the owner of examined fish.
Surveys of pond fish populations by sampling for presence of pathogens and diseases throughout the production cycle, with the purpose to identify the health status and eventual needs for preventive treatments. In this way detect specific season - and age - dependent health problems of fish in mono-and polyculture.
Cooperation with scientists in the centre in their work on various aspects of aqua-culture by checking fish health in experiments and recommending prophylactic and therapeutic treatments and advising on health protection measures in planning and conducting research.
One scientist, e.g., D. Kumar, should be assigned to the work described below.
Registering samples for virological examination, recording of methods applied and of findings, release of virological diagnosis for setting up final diagnosis. Making recommendations for prevention. Preparing of annual report on diagnostic work and research.
Preparation of media and solutions for cell culture work. Subcultivation, maintenance and cryopreservation of existing suitable American and European fish cell lines. Preparation of primary cell cultures from indigenous and other cultivated fish species. Development of fish cell lines from indigenous and other important species for this region.
Extraction of virus and decontamination of inocula for cell cultures or experimental fish. Inoculation of cell cultures, incubation and detection of virus presence. Presumptive and confirmative identification of virus, using morphological, cultural, biochemical and serological characterization. Inoculation of fish, observation of results.
Research on and development of advanced and improved fast virological methods. Use of rabbits for preparing of antisera.
Study and description of viral disease entities by using epizootiological, pathoanatomical, histopathological, virological and serological methods, and biological experiments in aquariums, tanks and ponds.
Surveys of pond fish populations for presence of viral pathogens and diseases in various phases of aquaculture technology. Detection of virus carriers among broodstock and fingerlings.
One scientist, e.g., K. Suresh, should carry out the work described below.
Registration of samples for bacteriological or mycological examination; recording of method used and findings; quick release of presumptive (if possible also confirmative) microbiological diagnosis for use of setting up final diagnosis, and recommendations for treatment and prevention. Keeping records on recommendations and experiments. Preparing annual report on diagnostic work and research. Preparation of methodology sheets.
Preparation of media and solutions for isolation of various pathogens, determination of their biochemical characteristics essential for classification and diagnosis and for maintenance of isolates. Preparation of stains and staining of smears.
Plating of materials and isolation of pure cultures. Examination of characteristics of isolates (morphology, culture, biochemical and staining characteristics), performing of tests for serological identification.
Research on development of advanced and improved bacteriological diagnostic methods, including immunological and immunofluorescent ones.
Study and description of bacterial and fungal disease entities by epizootiological, pathohistomical, histopathological, microbiological and serological methods, and biological experiments in aquariums, tanks and ponds. Determination of pathogenicity and virulence of isolates.
Surveys of pond fish populations for presence of bacterial pathogens and diseases in various phases of aquaculture technology.
Study of normal bacterial flora of species in aquaculture (skin, gills, intestines, blood) and its role in diseases.
One scientist, e.g., B.K. Mishra, should carry out the work described below.
Registration of samples for parasitological examination, recording of findings, quick release of parasitological diagnosis for use in setting up final diagnosis and recommendations for treatments. Keeping records on findings, recommendations and experiments. Preparing annual report on diagnostic work and research. Preparation of methodology sheets (procedures).
Application of various parasitological methods (flotation, digestion, concentration) for detecting protozoan parasites; fixation, staining and taxonomic examination of parasites.
Study of life cycles and ecology of parasites in pond culture, as well as epizootiology of diseases caused by them. Qualitative and quantitative surveys of parasitofauna in various stages of aquacultural technology.
Defining disease entities caused by parasites (epizootiology, histophathology, etc.). Aquarium and pond experiments on these diseases.
One scientist, e.g., R.K. Dey, should carry out the work described below.
Registering samples taken for histopathological examination, recording of methods used and of findings, quick release of histopathological diagnosis for setting up final diagnosis. Preparing annual report on diagnostic results and research.
Preparing of fixatives, histological stains and solutions, shaping up tissues for slicing, slicing by freezing microtome, embedding of samples in paraffin, preparation of paraffin sections, staining, mounting, microscopic examination, case studies and diagnostic work, preparing photomicrographs of sections.
Preparation of methodology sheets (procedures). Study of normal histology of various fish species of importance for aquaculture. Study and description of histopathology in individual disease entities caused by various etiological agents (including nutritional and toxic ones).
Cooperation with fish nutritionists and other research groups by providing histopathological expertise on status of organs in various experiments.
All four scientists should carry out the work described below.
Preparation of lists of drugs for prevention and treatment of fish diseases with indication of source, price and cost of treatment.
Planning and conducting tests on suitability of various drugs for prevention and treatment of diseases in aquariums, tanks and ponds. Keeping records on tests, evaluation of results.
Preparing and giving recommendations on prevention and treatment of diseases in field situations. Keeping records on such treatments and evaluation of results.
Improvement of techniques for treatment of fish by bath, by food and by mass injections.
Accumulation of documentation for research reports, papers, training purposes and extension work should be a constant activity of scientists in the unit. This, as well as collection, maintenance and preservation of pathogens is also necessary for national and international exchange with fish disease laboratories. A reference laboratory for fish diseases does not exist in this part of the world and the FARTC may assume this role through the unit.
Setting up a museum of wet preparations of sick fish, collection of pictures of gross lesions and microscopic in fish, maintenance of fish cell cultures, storage of virus isolates, bacterial pathogens, specimens of parasites, histopathological slides, etc., should be a part of efforts to upgrade the quality of their own work.
The unit should have a small library, consisting of books on methodologies used (virology, bacteriology, parasitology, histopathology, etc.) and on fish diseases. A collection of reprints and a reference card system, arranged according to groups of diseases and related problems, should also be set up at the unit level. Adequate information about a suitable system was suggested to workers by the consultant during the training.
One senior scientist (V.R.P. Sinha), specialist for composite fish culture, plus all four scientists of the unit.
The objectives are to develop methods of assessing the health status and the occurrence of subclinical and clinical diseases from the stocking to the fishing out of ponds.
By determining health status and specific disease problems, possibilities will be opened for application of prevention and treatments, thus increasing chances for higher yields. Results of monitoring will also indicate high priority research problems in the field of fish diseases.
The monitoring should be carried out in three production ponds with high stocking density managed for intensive culture.
Monitoring at three levels will be carried out and compared:
(i) Fish culturist level (farm workers). Daily observation of ponds for fish in distress or dead fish; daily observation of food intake; immediate notification of unit about unusual observations or drop in food uptake.
(ii) Aquaculture specialist level. Extension worker should observe the pond situation at least once every ten days and check fish for growth rate and general appearance by netting at one month intervals. At stocking and at fishing out, the number of fish should be precisely determined to calculate exactly the percentage of loss for correlating this with findings about fish health. Notification of unit when unusual findings are present.
(iii) Fish disease specialist level. To determine the health status and detect disease or parasite incidence at a 10 percent or higher level, a sample of 30 fingerlings of each species will be examined in the laboratory before stocking and 30 specimens of each species will be examined in the laboratory at bimonthy intervals and at fishing out.
In the unit, the following examinations will be undertaken: total length, weight and condition (Fulton's formula) of each specimen; determination of hematocrit value; dissection, macroscopic and microscopic examination of organs for detecting abnormal appearance of organs and presence of parasites; bacteriological examination of lesions (if they exist) and of kidneys of five fish from each species sample; histopathological sampling of abnormal looking organs, and sampling for virology if symptons suspective for a viral disease exist.
Results will be summarized and the situation in the three ponds compared.
Three years, with extension after necessary adjustments.
One (D. Kumar).
The objectives are the development of standard methodology for fish cell culture work and virology in cultivated Indian carps.
It is highly probable that viral diseases will start to occur in fish culture. Their detection, identification and study is impossible without cell culture work. This research is also needed for later development of vaccines for prevention of viral diseases.
Methodology for preparing glassware, media and other items for cell culture work and virology will be modified to suit local conditions;
Asceptically taken ovaries and other organs will be used for explant and for trypsinization technique of obtaining monolayers of cells; developing and adopting methods suitable for Indian major carps;
Primary cell cultures and foreign cell lines will be kept at various temperatures, subcultivated and maintained;
Methods will be developed and standardized for inoculation of cultures with material from diseased and suspect fishes from ponds.
Three years, with extension after revision.
One (K. Suresh).
The objectives are the development and improvement of bacteriological research methods for study of fish diseases.
Diseases have been noted in composite culture that are probably of bacterial etiology. By the above research on suitable methodologies, it will become possible to detect these diseases, to study them, diagnose them quickly and provide the fish culturist with information about prevention and treatment.
Comparison of suitability of various bacteriological media for isolation of various groups of fish pathogens from external lesions (skin, gills) and internal organs (kidney, liver, heart);
Selection and testing of biochemical tests for identification of fish pathogens;
Development of immunological methods for identification of bacterial pathogens, using rabbit hyperimmune sera;
comparison of suitability of several commercially available or other media for maintenance of isolates.
One (B.K. Mishra).
Sensitive and reliable methods for detecting and identifying internal protozoan and methazoan parasites in Indian major carps will be developed.
Information on diseases caused by parasites is restricted in India mostly to skin and gill pathology. It is, therefore, necessary to develop methods for early detection, concentration, storage and staining of potentially harmful internal parasites. These methods will enable carrying out properly the fish health monitoring and expanding research on diseases damaging fish culture, thus opening possibilities for prevention and treatment.
Blood parasites - development of techniques for taking blood, preparing smears and staining them for blood parasites;
Intestinal cocedia - detection, concentration and staining of spores;
Myxosporidia - detection, digestion methods, concentration and comparison of various staining methods for myxosporidia in kidneys and other organs.
One (R.K. Dey).
The objectives are to determine the suitability of major histopathological staining methods for study of pathological changes in two major organs of carps.
Most systemic bacterial and viral diseases of fishes, some localized parasitic diseases and nutritional deficiencies manifest themselves by histological alterations in these two organs. The comparison of results obtained by various staining methods on material from large number of fishes will allow choosing standard stains for examining these organs for routine and specific purposes.
Organs collected from 40 healthy and 40 sick specimens of each species of Indian major carp will be fixed by buffered formalin and Bouin's fluid;
Paraffin and freeze - sections of organs will be stained by hematoxilin-eosin, PAS, PAS alcain-blue, Malloxy, Sudan black and Masson's trichrome stain;
Stained sections will be evaluated for suitability to study normal and altered histology of kidney and liver.
|1. Dr V.R.P. Sinha and Dr N. Fijan||Introduction|
|2. Mr R.N. Pal||Causes and consequences of fish diseases in aquaculture|
|3. Mr B.K. Mishra||Fish health monitoring by field observations and laboratory diagnostic work|
|4. Mr D. Kumar||Collecting, packing and transport of samples to diagnostic laboratory|
|5. Mr K. Suresh||Principles of disease prevention in pond culture|
|6. Mr R.K. Dey||Treatment of fish diseases|
|7. Mr D. Kumar||Vaccination of fish.|