There is an urgent need in aquaculture to develop microbial control strategies, since disease outbreaks are recognized as important constraints to aquaculture production and trade and since the development of antibiotic resistance has become a matter of growing concern. One of the alternatives to antimicrobials in disease control could be the use of probiotic bacteria as microbial control agents. This review describes the state of the art of probiotic research in the culture of fish, crustaceans, mollusks, and live food, with an evaluation of the results obtained so far. A new definition of probiotics, also applicable to aquatic environments, is proposed, and a detailed description is given of their possible modes of action, i.e., production of compounds that are inhibitory toward pathogens, competition with harmful microorganisms for nutrients and energy, competition with deleterious species for adhesion sites, enhancement of the immune response of the animal, improvement of water quality, and interaction with phytoplankton. A rationale is proposed for the multistep and multidisciplinary process required for the development of effective and safe probiotics for commercial application in aquaculture. Finally, directions for further research are discussed.

/pdf/probiotic-bacteria-as-biological-control-agents-in-4778jdx241.pdf

Probiotic Bacteria as Biological Control Agents in Aquaculture

Physiological changes in fish from stress in aquaculture with emphasis on the response and effects of corticosteroids

The results of the meetings of the International Committee on Taxonomy of Viruses, held in Madrid, September 1975, are briefly reported: rules of viral nomenclature, composition of the new Executive Committee, and a list of the names so far officially agreed. Introduction The International Committee on the Taxonomy of Viruses (ICTV), which is a committee of the Section on Virology of the International Association of Microbiological Societies (IAMS), completed a round of meetings during the Third International Congress for Virology that was held in Madrid from September 10--17, 1975. Since ICTV only meets during these conferences, which are held every four years, the meetings are important occasions for reviewing the classification and nomenclature of viruses. Decisions on new names, which encapsulate the recognition of natural "groups" of viruses, evolve slowly. Official approval for new names depends upon a series of sequential steps ; recommendations by one or more of the subcommittees of the Executive Committee of ICTV (subcommittees on Bacterial, Invertebrate, Plant and Vertebrate Viruses respectively, and for some of the larger viral groups which span several kinds of hos t s the Coordination Subcommittee), which are considered by the Executive Committee of ICTV and may finally be submitted for approval by ICTV itself. Only after this final approval does a name become "official". The results of the last five years of work by ICTV and its committees will be published early this year as a separate volume of "Intervirology", the official journal of the Section on Virology of IAMS, and additional copies will be produced for sale as separates. This "Second P~eport" will include, besides "approved" and common names of virus groups, a brief description of the properties of each

Classification and Nomenclature of Viruses

Current research status of fish immunostimulants

Preface. Selected Atomic Weights. Customary Metric Conversion Factors. 1. Water Quality and Aquaculture: Preliminary Considerations. 2. Ecology of Aquaculture Ponds. 3. Water Quality Requirements. 4. Water Use. 5. Liming. 6. Fertilization. 7. Aeration. 8. Water Circulation. 9. Turbidity and Appearance of Water. 10. Aquatic Weed Control. 11. Off-Flavors and Harmful Algae. 12. Pollution. 13. Chemical, Physical, and Biological Treatments. 14. Waste Management. 15. Measurement of Water Quality. 16. Sustainability and Environmental Issues. References. Index.

Pond aquaculture water quality management

About the Authors Preface. Acknowledgments. Part I: Health Maintenance. 1 Principles of Health Maintenance. 2 Epizootiology of Fish Diseases. 3 Pathology and Disease Diagnosis. 4 Disease Management. Part II: Viral Diseases. 5 Catfish Viruses. 6 Carp and Minnow Viruses. 7 Eel Viruses. 8 Trout and Salmon Viruses. 9 Sturgeon Viruses. 10 Other Viral Diseases of Fish. Part III: Bacterial Diseases. 11 Catfish Bacterial Diseases. 12 Carp and Minnow Bacterial Diseases. 13 Eel Bacterial Diseases. 14 Salmonid Bacterial Diseases. 15 Striped Bass/Hybrid Bacterial Diseases. 16 Tilapia Bacterial Diseases. 17 Other Bacterial Diseases. Part IV: Appendices. Appendix I. List of Common and Scientific Names of Fishes. Appendix II. Table of Conversion Factors. Appendix III. List of Cell Lines Commonly Used for Diagnostics. Index.

Health Maintenance and Principal Microbial Diseases of Cultured Fishes

Channel catfish, Ictalurus punctatus, were injected intraperitoneally with a sublethal dose of Aerornonas hydrophila and then stressed for 144 h by being maintained either in a dissolved oxygen concentration of 1·5 mg/1, 1·2 mg/1 total ammonia, and/or 6·5 mg/1 free CO2 with a continuous inflow of water. A significant difference in percentage of mortality was noted between treatments (P < 0·05). The trunk kidneys of surviving stressed fish had significantly higher total bacterial counts than non-stressed controls. A. hydrophila was isolated from 67% of the stressed fish and 9% of the control fish. Edwardsiella tarda, apparently endemic in the population, was isolated from 43% of the stressed fish and 7% of the control fish. Histopathological lesions were in the gills, liver, spleen, trunk kidney, and head kidney of stressed fish, but not control fish.

Environmental stress and bacterial infection in channel catfish, Ictalurus punctatus Rafinesque

During July through September 1995, about 1,000 adult largemouth bass Micropterus salmoides died in Santee-Cooper Reservoir, South Carolina. Necropsy of two moribund largemouth bass (each weighing about 2 kg and measuring about 50 cm) revealed no parasites or bacterial infection. Fathead minnow (FHM) cell cultures inoculated with filtered homogenate from the swim bladder of one fish and the swim bladder and liver of the second fish developed cytopathic effect 48 h after inoculation. Media from infected cell cultures contained up to 108.9 TCID50/mL of a 0.45-μm filterable agent (TCID50 is the tissue culture infective dose that affects 50% of innoculated cultures). Electron microscopy of infected FHM cells revealed a cytoplasmic, icosahedral virion that averaged 132 nm from facet to facet and 145 nm from corner to corner. Viruses acquired an envelope upon passing through the plasma membrane. Studies of virus replication inhibition by pyrimidine analogs were inconclusive in classifying the nucleic a...

An Iridovirus Isolated from Wild Largemouth Bass

. Fingerling channel catfish, Ictalurus punctatus (Rafinesque), were exposed experimentally to Edwardsiella ictaluri by immersion for 1 h in water containing 5 × 108 colony-forming units (CFU) of the bacterium per ml. Ninety per cent of the fish developed lesions typical of enteric septicaemia of catfish (ESC), 93% of affected fish developed the acute form of ESC and 7% developed chronic ESC. Acute disease was characterized grossly by cutaneous haemorrhage and ulceration, and microscopically by enteritis, olfactory sacculitis, hepatitis and dermatitis. The earliest lesions of acute ESC, i.e. enteritis and olfactory sacculitis, were observed microscopically at 2 days post-exposure (PE); gross lesions, primarily mild subcutaneous haemorrhage at the base of fins, were first apparent at 4 days PE. Chronic ESC, seen most commonly 3–4 weeks PE, was characterized by dorsocranial swelling and ulceration, granulomatous olfactory neuritis/perineuritis, and meningoencephalitis involving the olfactory bulbs, olfactory tracts and olfactory lobes of the brain. Gross and microscopic lesions in the acute and chronic forms of experimental ESC were similar to the lesions reported in naturally occurring ESC. Definitive pathogenesis of acute and chronic ESC remains to be determined.

Pathology of experimental enteric septicaemia in channel catfish, Ictalurus punctatus (Rafinesque), following immersion-exposure to Edwardsiella ictaluri.

Fish kills in estuarine bays along the Florida and Alabama Gulf Coast were investigated in August and September 1972. Eight species of moribund fish were examined. A nonhemolytic, group B, type Ib Streptococcus sp. was isolated from over 90% of the fish examined. Parasites and toxicants were eliminated as possible causes of the kills.

John A. Plumb

Papers

Health Maintenance and Principal Microbial Diseases of Cultured Fishes

Environmental stress and bacterial infection in channel catfish, Ictalurus punctatus Rafinesque

An Iridovirus Isolated from Wild Largemouth Bass

Pathology of experimental enteric septicaemia in channel catfish, Ictalurus punctatus (Rafinesque), following immersion-exposure to Edwardsiella ictaluri.

Streptococcus sp. from Marine Fishes Along the Alabama and Northwest Florida Coast of the Gulf of Mexico