Studies on the freshwater copepod fish parasites of Kerala

Studies on parasitic copepods from freshwater fishes are still in its infancy. In recent years, there- is a renewed enthusiasm in the study of freshwater fish parasites due to rapidly increasing aquaculture practices. The importance of diseases and their control assumes great significance because of the adverse impact of diseases on fish production and its economy. Copepods are one of the most harmful parasites of freshwater fishes. Reports on the damages caused by copepod parasites from different parts on the world are increasing alarmingly. But the information on parasitic copepods of freshwater fishes in India is quite meagre. Knowledge regarding this group of parasites, their Biology and pathology from Kerala. is lacking. The thesis consists of five chapters. The first chapter is a general introduction which deals with the review of literature on various aspects of parasitic copepods viz; systematics, life history, host-parasite relationship, ecology, pathogenicity, prophylaxis and control measures. Systematics of parasitic copepods of freshwater fishes collected during the present study forms the second chapter. The third chapter deals with the life cycle study of the new Lernaeid copepod, Lernaea osphronemi. The fourth chapter contains host-parasite relationship. ecology and treatment of ‘the’ new species of Lernaea On Osphronemus goramy. General observations and a summary of the entire work constitute the fifth chapter

Technology transfer in the fish curing industry in india

Curing is the oldest and cheapest method of preservation of fish allover the world. Fish curing industry has not shown much improverrent from its primitive nature because this industry is mainly handled by illiterate and less educated fishermen/fisherwomen. They do not know much about,the importance of scientific methods of fish curing. The cured fish produced by them is unhygienic and poor in quality. Because of the negligenence and ignorance of the fish curers, a considerable quanti ty of this protein rich food is spoiled and lost every year. Research has been conducted extensively in the Cen tral and State sectors and various remedial measures have been suggested :to improve the fish curing industry in India. Inspi te of the preJudioa against cured fish because of their existing low quality, research work in recent years have indicated that their quality can be greaUy improved and shelf-life prolonged if the me thods are standardised. To achieve this aim, Cen tral and s tate Departments have already made considerable efforts to transfer the improved methods ~ the fish curing industry by way of traininq courses, demonstrations, Lab, to Land Prograrrmesi film shows, exhibitions, personal discussion etc. As the result of this, fish curers have started adopting the improved practices in fish curing. Still there seems to be a considerable qap between the techmology available and the technology adopted in this field. A comprehensive study on the extent of adoption of improved practices in fish curing and the factors involved in low or non-adoption of certain aspects is lackin~ at present. This gap has to be filled up. The possihle methods for the effective transfer of technology for the production and distribution of high quali ty cured fish products and improvement of soclo-economic condition of fishermen engaqed in fish curing have to be identified.

Studies on fish lipases

Lipids constitute a significant portion of the biomass of earth and lipolytic enzymes play a very important role in lipid turn over. Apart from their biological significance, lipolytic enzymes are also very important in the fields of nutrition, food technology, medicine and preparative and analytical lipid biochemistry. Recent developments in the study of proteins and enzymes have largely benefited the study of lipolytic enzymes, that some of these enzymes were isolated in pure form. Even today there is a continuous search for new and potent sources of these lipolytic enzymes. The zest for elucidating the structure and mechanism of action of the enzymes obtained in pure form for biochemist still remains unabated. The literature shows no record of such an effort for the study of lipases from marine sources. The fact that many fishes like oil sardine, mackerel, cat fish, seer etc. contains large amounts of lipid shows the possibility of the existence of lipases in significant amounts necessitating their exhaustive study. Such a study will, not only provide alternate sources for lipase but also will provide methods to curb lipolysis and the resultant rancidity and off flavor development in fish and fishery products.

‘Systematics and pathogenicity of Vibrionaceae associated T ¢ S with the larvae of M. rosenbergii in hatchery

Even though Bergey '5 Manual has been recognized globally as the guide to bacterial systematics, it has to be emphasized that descriptions given to a large extent are based on studies made with temperate isolates This leads one to conclude that any attempt to identify the tropical isolates with identification keys and tables generated from this information may lead to erroneous conclusions. And there is every possibility of the existence of genotypic and phenotypic variants or even nev. species in this part ofthe aquatic ecosystem. Applications ofa polythetic scheme of classification based on the principles of Numerical Taxonomy opens up exciting avenues for bringing to light, this possibility which otherwise would have been masked by the unidirectional approach as in monothetic schemes. Another added advantage of clustering a ‘natural’ bacterial population by numerical taxonomy, is the ease by which genotypic characterization could be performed on the clusters by selecting a representative from each cluster This helps overcome the practical impossibility of analyzing all the isolates in a pani:'_lar cluster. The genotypic characteizarion would either be mole °/o G-'rC. DNA-D.\_-X hybridization, DNA-RNA hybridization or DNA fingerprinting. Considering the requirement creating a broad base in the understanding of the family Vibrionaceae associated with the larvae ofM rosenbergii, the present work was undertaken to channelize every new information generated for developing appropriate managerial measures to protect the larvae from vibriosis during the unusually prolonged larval phase.

Studies on The Eco Biology of The Indian Pearl Oyster, Pinctada Fucata (Gould)

The present work aims to study induced maturation of the pearl oyster for induced spawning experiments. The work on larval development was done with a view to developing techniques for the artificial rearing of commercially important pearl oyster P fucata, and also to elucidate the principles and problems of tropical bivalve larvae in general for detailed investigations in the future. The present study is designed to probe into the details of the basic aspects of the biology related to the hatchery technology of Pinctada fucata and the understanding of the factors which influence induction of maturation, spawning, larval rearing and spat settlement. This would go a long way in the upgradation of hatchery technology of the Indian Pearl oyster Pinctada fucata fora commercial level seed production..

Materials for Fish Nets-Their Properties, Selection and Preservation

The properties of synthetic fibres vary with thc inherent physical characteristics of the basic raw materials used mode of preparation of yarns and method of construction of twines. Since the synthetic fibres as maufactured from polymers which are synthesized from simple chemical units, the qualities of man-made fibres can he influenced by the process of manufacture and certain modifications can even be introduced at the processing stage to meet any specific requirement to a certain extent. Hence, an elaborate study of the properties of fish not twines produced has been taken up with a view to determining their suitability for various types of fishing gear with particular reference to conditions prevailing in India.

Enzyme reactions as index of freshness of Fish and Shellfish

An attempt has been made in this study to screen some fish muscle enzymes to assess their potential worth in testing the degree of freshness of fish. A problem with routine enzyme activity determinations is the complexity of the method of enzyme assay. Hence, in the present study as far as possible simple assay techniques were adopted. Several species were screened to assess the possibility of employing this procedure on a large scale. It is hoped that findings of this study will lead to the development of meaningful criteria in testing the freshness of fish. This thesis has been divided into five chapters

Effect Of Raw Material Quality On The Shelf Life Of Frozen Stored Fish And Fishery Products

Frozen storage characteristics and shelflife vary considerably among species as well as within the species (Powrie, 1973; Fennema. 1973). This can be attributed to the variation in the composition of fish among various species. In certain species like sardines and mackerel. wide seasonal variation in chemical composition occur within the species. These variations affect the quality and shelflife. The nutritional level of water. spawning, method of catching, struggling etc. are found to have profound influence on the condition of the fresh fish. Soon after death the deteriorative changes in fish start due to autolysis and bacterial growth. The rate of these changes depends mainly on temperature. The handling methods have great influence on bacterial contamination. Thus the type oi'handling. temperature control. period of chill storage. processing methods. type of freezing, condition of frozen storage and period of storage affect the quality and shelflife Of the fisho In the present study extensive investigations were carried out on various factors affecting the quality of fish as well as their effect on the physical. chemical and sensory qualities of fish during frozen storage and the shelflife

Haematological and Toxicological studies on brackish water fish Etroplus maculatus (Bloch)”

Fishes are one of the most important members of the aquatic food chain, and through them some toxicants may reach human beings as well. The selection of organisms for toxicity test is mainly based on certain criteria like its ecological status, position within the food chain, suitability for laboratory studies, genetically stable, uniform populations and adequate background data on the organism (Buikema et al., 1982). The species selected for the present study Etroplus maculatus satisfy most of the above protocols. Rechten (1980) opined it as a laboratory favorite of fish researchers. However, there are difficulties in the rise of fishes for pollution assessment impact. Most important of these is our limited understanding of the mechanism of toxicity. The interpretation of the significance or specificity of a measured biological response could there for become difficult. Not withstanding these limitations, attempts have been made to the normal haematology and to analyze the impact of heavy metal at realistic levels to the experimental media, on the haematology, and enzymatic activity and histology of Etroplus maculatus

“Effects of monospecific and mixed algal diets on survival, development and biochemical composition of Penaeus monodon larvae”

The main objective of the present work is to acquire information regarding the growth responses of P. monodon larvae (from PZ1 upto PL1) to various mono specific and mixed diets. Evaluate the nutritional quality of selected species of micro algae viz. Chaetoceros calcitrans, Dunaliella salina, Isochrysis galbana and Nannochloropsis salina, larvae at three cell concentrations 10x104 cells/ml, 25x104 cells/ml and 50x104 cells/ml. The P. monodon larvae were transported, at the Nauplius stage, to the laboratory. The larvae were stocked at density of 150 larvae per litre in 5 litre FRP tanks with 3 litres of sea water. The algal cell density given to the larvae varied. The larval stages were fed with increasing densities of algae to evaluate the relationship between the food densities, ingestion rates, development and growth of the larvae. The water quality parameters, the percentage of survival rate, the growth estimation and the algal cell count were done. Each experiment was carried out in triplicate with a control group of larvae fed with Chaetoceros calcitrans. For the estimation standard procedures were used.to P. monodon

Systematics and pathogenicity of vibrionaceae associated with the larvae of macrobrachium rosenbergii in hatchery

The great potential for the culture of non-penaeid prawns, especially Macrobrachium rosenbergii in brackish and low saline areas of Indian coastal zone has not yet been fully exploited due to the non availability of healthy seed in adequate numbers and that too in the appropriate period. In spite of setting up several prawn hatcheries around the country to satiate the ever growing demands for the seed of the giant fresh water prawn, the supply still remains fear below the requirement mainly due to the mortality of the larvae at different stages of the larval cycle. In a larval rearing system of Macrobrachium rosenbergii, members of the family Vibrionaceae were found to be dominant flora and this was especially pronounced during the times of mortality However, to develop any sort of prophylactic and therapeutic measures, the pathogenic strains have to be segregated from the lot. This would never be possible unless they were clustered based on the principles of numerical taxonomy It is with these objectives and requirements that the present work involving phenotypic characterization of the isolates belonging to the family Vibrionaceae and working out the numerical taxonomy, determination of mole % G+C ratio, segregation of the pathogenic strains and screening antibiotics as therapeutics at times of emergency, was carried out.

Diversity and antimicrobial activity of Lactic Acid Bacteria from the gut of marine fish Rastrelliger kanagurta against fish, shrimp and human pathogens

Emergence of antibiotic resistance among aquaculture pathogens has made it necessary to look into environment friendly, effective and sustainable methods such as probiotic and immunostimulants among others.. In the present study, LAB were isolated from the gut of fish species namely Rastrelliger kanagurta and analyzed for their antibacterial activity against various fish, shrimp and human pathogens. Different LAB species such as Lactobacillus plantarum, L. bulgaricus, L. brevis and L. viridiscens were encountered in the gut of R. kanagurta. Several strains showed good activity against fish, shrimp and human pathogens. LAB from the gut of such marine species may be developed as possible probiont for environment friendly health management of fresh water, estuarine and marine species currently exploited in aquaculture

Gut Associated Lactic Acid Bacteria Isolated from the Estuarine Fish Mugil cephalus: Molecular Diversity and Antibacterial Activities against Pathogens

In the present study we address the issue on gut associated lactic acid bacteria (LAB) isolated from the intestine of estuarine fish Mugil cephalus using de Man Rogossa and Sharpe (MRS) agar. LAB isolates were identified biochemically and screened for their ability to inhibit in vitro growth of various fish, shrimp and human pathogens. Most of the LAB isolates displayed an improved antagonism against fish pathogens compared to shrimp and human pathogens. Selected representative strains displaying high antibacterial activity were identified using 16S rRNA gene sequence analysis. Of the selected strains Lactobacillus brevis was the most predominant. Four other species of Lactobacillus, Enterobacter hormaechei and Enterobacter ludwigii were also identified. It was also observed that even among same species, considerable diversity with respect to substrate utilization persisted. Considering the euryhaline nature of grey mullet (Mugil cephalus), the LAB isolated from the gut possessed good tolerance to varying salt concentrations. This finding merits further investigation to evaluate whether the isolated LAB could be used as probiotics in various fresh and sea water aquaculture

Prevalence of Salmonella in fish and crustaceans from markets in Coimbatore, South India

Seven hundred and thirty fishes and 276 crustaceans collected from various fish markets of Coimbatore, South India, over a period of 2 years (September 1990 to August 1992) were analysed for the prevalence of Salmonella. Fishes (14·25%) and 17·39% of crustaceans were found to be contaminated with Salmonella. Of the different fishes analysed, the highest incidence of Salmonella was seen in Scopelidae (28%) followed by Trachnidae (26·9%). Among crustaceans Portunus pelagicus (33·33%) showed the highest incidence followed by Scylla serrata (28·57%). A well-marked seasonal variation in the incidence pattern was observed in both fishes and crustaceans with a higher incidence during monsoon season followed by post-monsoon and pre-monsoon. The region of the body that showed frequent isolation was the alimentary canal in fishes (41·33%) and gills (35·06%) in crustaceans. Serotyping of the isolates revealed prevalence of Salmonella weltevreden, Salmonella typhi, Salmonella paratyphi B, Salmonella mgulani and Salmonella typhimurium in both fishes and crustaceans. Salmonella senftenberg was isolated only from crustaceans

Antibiotic resistance pattern of motile aeromonads from farm raised fresh water fish

Motile aeromonads isolated from the intestines of farm-raised freshwater fish such as Catla catla, Labeo rohita and Ctenopharyngodon idella have been characterized to species level. Morphological and physiological grouping revealed 61% Aeromonas hydrophila, 30% Aeromonas caviae, 7% Aeromonas sobria and 2% which remained unidentified. Hemolytic activity was detected mostly in A. hydrophila, while only half of the A. sobria and A. caviae showed this activity. Antibiotic resistance patterns of the strains revealed that they had acquired a relatively higher resistance to oxytetracycline, amoxycillin, ampicillin, novobiocin and polymixin-B, implicating possible use of these antibiotics in the aquaculture systems.