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

Unsustainable fishing practices have placed a heavy emphasis on aquaculture to meet the global shortfalls in the supply of fish and seafood, which are commonly accepted as the primary source of health-promoting essential omega-3 (n-3 highly unsaturated fatty acids). However, dietary fish oil is required for the production of omega-3-rich farmed fish and this commodity, in a vicious circle, is at present derived solely from wild fisheries. Decreasing global availability coupled with the highly variable price of this resource has forced the aquaculture industry to investigate the possibilities of alternative dietary lipid sources. This review attempts to compile all principal information available regarding the effects of fish oil replacement for the diets of farmed finfish, analysing the findings using a comparative approach among different cultured fish species. The review initially focuses on the present situation with regard to the production, availability and main nutritional characteristics of fish oil and the principal alternative lipid sources (such as vegetable oils and animal fats). Following this, the effects of fish oil replacement in finfish nutrition on feed quality, fish performance, feed efficiency, fish lipid metabolism, final eating quality and related economic aspects are presented and discussed.

Fish oil replacement in finfish nutrition

This introductory text on the design and analysis of sample surveys emphasizes the practical aspects of survey problems. It begins with brief chapters on the role of sample surveys in the modern world. Thereafter, each chapter introduces a sample survey design or estimation procedure by describing the pertinent practical problem. The authors describe the methodology proposed for solving the problem and provide the details of the estimation procedure, including a compact presentation of the formulas needed to complete the analysis. Then, a practical example is worked out in complete detail. At the end of each chapter, a wealth of exercises gives students ample opportunity to practice the techniques and stretch their grasp of ideas.

Elementary Survey Sampling

The worldwide growth of aquaculture has been accompanied by a rapid increase in therapeutic and prophylactic usage of antimicrobials including those important in human therapeutics. Approximately 80% of antimicrobials used in aquaculture enter the environment with their activity intact where they select for bacteria whose resistance arises from mutations or more importantly, from mobile genetic elements containing multiple resistance determinants transmissible to other bacteria. Such selection alters biodiversity in aquatic environments and the normal flora of fish and shellfish. The commonality of the mobilome (the total of all mobile genetic elements in a genome) between aquatic and terrestrial bacteria together with the presence of residual antimicrobials, biofilms, and high concentrations of bacteriophages where the aquatic environment may also be contaminated with pathogens of human and animal origin can stimulate exchange of genetic information between aquatic and terrestrial bacteria. Several recently found genetic elements and resistance determinants for quinolones, tetracyclines, and β-lactamases are shared between aquatic bacteria, fish pathogens, and human pathogens, and appear to have originated in aquatic bacteria. Excessive use of antimicrobials in aquaculture can thus potentially negatively impact animal and human health as well as the aquatic environment and should be better assessed and regulated.

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Antimicrobial use in aquaculture re‐examined: its relevance to antimicrobial resistance and to animal and human health

Enteric septicemia of catfish (ESC) and columnaris are the most economically important bacterial diseases affecting the channel catfish Ictalurus punctatus industry in the United States. Although these two diseases have been extensively researched, little is known about their prevalence and epidemiology in production systems. In 1997, a two-part survey of catfish producers in Alabama, Arkansas, Louisiana, and Mississippi was conducted to estimate the proportion of ponds and catfish operations that have these diseases and to develop information on the risk factors associated with reporting an occurrence. The response rates to the two phases of the survey were 65.6% and 75.3%, respectively. Overall, 78.1% of all operations and 42.1% of all ponds experienced problems with ESC/columnaris. Higher percentages of large operations and ponds on large operations experienced these problems. The most frequently reported average loss per outbreak of the two diseases was 200–2,000 lb (1 lb = 0.454 kg) per outb...

The Epidemiology of Bacterial Diseases in Food-Size Channel Catfish

Juvenile Norris strain channel catfish Ictalurus punctatus, blue catfish I. furcatus, and Norris strain channel catfish female × blue catfish male hybrids were challenged with Edwardsiella ictaluri by bath immersion or intraperitoneal injection (high or low dose) in aquaria. Survival (%) after bath immersion was highest for blue catfish (89.5 ± 2.8), intermediate for hybrids (73.8 ± 6.7), and lowest for channel catfish (62.0 ± 4.2). Prechallenge antibody levels to E. ictaluri, measured by enzyme-linked immunosorbent assay, were negative (mean ± SE optical density [OD] = 0.010 ± 0.003). Postchallenge antibody response for blue catfish (OD = 0.132 ± 0.045) was significantly lower than that of channel catfish (OD = 0.350 ± 0.045), whereas the response of the channel × blue catfish F1 hybrids (OD = 0.263 ± 0.051) was intermediate and not significantly different from either parental species. Intraperitoneal injections of E. ictaluri resulted in significant mortality only in channel catfish (88.3 ± 2.6...

Survival and Antibody Response of Channel Catfish, Blue Catfish, and Channel Catfish Female × Blue Catfish Male Hybrids after Exposure to Edwardsiella ictaluri

Fingerling channel catfish Ictalurus punctatus were fed purified diets either unsupplemented and deficient in both selenium and vitamin E, deficient in either selenium or vitamin E, adequate in both selenium (0.2 mg/kg) and vitamin E (60 mg/kg), or excessive in both nutrients (four times the recommended levels). After 115–120 d of feeding the experimental diets, the red blood cell membranes offish fed diets deficient in vitamin E were more susceptible to peroxidation than were those of fish fed diets that met or exceeded vitamin E recommendations. Hepatic, selenium-dependent glutathione peroxidase activity was suppressed in fish fed diets deficient in selenium when compared with this enzyme activity in fish fed diets containing recommended or higher levels of selenium. Intracellular superoxide anion production of macrophages was higher in fish fed the diet fortified with four times the recommended levels of both nutrients than in fish fed the other diets. None of the results indicated that seleni...

Effects of Dietary Selenium and Vitamin E on Red Blood Cell Peroxidation, Glutathione Peroxidase Activity, and Macrophage Superoxide Anion Production in Channel Catfish

Publisher Summary Channel catfish health management begins with creating and maintaining a proper living environment for the fish. Good management also includes the design and operation of a production facility that minimizes the impact of stress on the fish. To promote health and minimize stress, fish should be provided with their basic needs: sufficient space, good water quality, a nutritionally complete diet, limited physical disturbance, protection from predators, and prudent handling. Once these needs are met, it is important to limit contact with disease-causing agents and to prevent environmental deterioration. Even in well-designed and properly managed facilities, it is not uncommon for diseases to occur. Once a disease outbreak ensues, effective health management requires three basic steps: problem identification, diagnosis, and corrective management—all of which must be performed in a timely manner to avoid further losses. Whenever multiple factors contribute to the disease process, it makes the diagnosis more difficult and often complicates corrective management. Many fish health problems, such as oxygen depletions, can be recognized and corrected by the fish culturist on the pond bank. This chapter discusses factors affecting the disease process in catfish and steps that can be taken to diagnose disease problems. The chapter provides an overview of the various options for managing infectious diseases. Several specific management procedures for the important catfish diseases are also discussed.

David J. Wise

Papers

The Epidemiology of Bacterial Diseases in Food-Size Channel Catfish

Survival and Antibody Response of Channel Catfish, Blue Catfish, and Channel Catfish Female × Blue Catfish Male Hybrids after Exposure to Edwardsiella ictaluri

Effects of Dietary Selenium and Vitamin E on Red Blood Cell Peroxidation, Glutathione Peroxidase Activity, and Macrophage Superoxide Anion Production in Channel Catfish

15 Health management

Dietary menhaden oil reduced resistance of channel catfish (Ictalurus punctatus) to Edwardsiella ictaluri