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  • 2000-2004  (4)
  • 1
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A stock of rainbow trout, Oncorhynchus mykiss, held at an experimental facility, was found to be heavily infested with the lernmaeapodid copepod Salmincola californiensis. The efficacy and effects of treatment were compared with ivermectin or manual removal of parasites as a means of control of S. californiensis. One group of fish was orally intubated with 0.2 mg ivermectin active ingredient kg−1 fish. A second treatment was administered after a further 14 days. In a second group of fish, parasites were manually removed from the gills using forceps. These fish were sampled for up to 21 days post-first removal of parasites. In the ivermectin-treated fish adult parasites became inactive and changed colour within 18 h of the initial treatment. Copepods began to disappear by day 3 post-treatment and by day 31 almost all embedded female parasites had disappeared. Gills were clinically normal apart from cavitation deformity resulting from parasite attachment. Post-ivermectin treatment, there was an increase in the number of eosinophilic granular cells surrounding the bulla of attached S. californiensis, but from day 31 post-treatment these were replaced by macrophages and epithelioid cells to form a necrotic focus. In manually picked fish there was extensive haemorrhage in the interlamellar spaces as a result of parasite removal. At sites of parasite removal tissue necrosis was minimal and healing was rapid. At the end of the sampling period the structure of the gill was improved. The use of oral dosage with ivermectin is an effective treatment for S. californiensis and could be particularly beneficial for use with endangered salmon broodstocks infested with the parasite.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 26 (2003), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Melano-macrophage centres, also known as macrophage aggregates, are distinctive groupings of pigment-containing cells within the tissues of heterothermic vertebrates. In fish they are normally located in the stroma of the haemopoietic tissue of the spleen and the kidney, although in amphibians and reptiles, and some fish, they are also found in the liver. They may also develop in association with chronic inflammatory lesions elsewhere in the body and during ovarian atresia. In higher teleosts, they often exist as complex discrete centres, containing lymphocytes and macrophages, and may be primitive analogues of the germinal centres of lymph nodes. Melano-macrophage centres usually contain a variety of pigments, including melanins, and these increase in range and volume in older fish or in the presence of cachectic disease. Melano-macrophage centres act as focal depositories for resistant intracellular bacteria, from which chronic infections may develop. Iron capture and storage in haemolytic diseases appears to be a primary function, but antigen trapping and presentation to lymphocytes, sequestration of products of cellular degradation and potentially toxic tissue materials, such as melanins, free radicals and catabolic breakdown products are among other functions that have been ascribed. Recent work suggests that they are a site of primary melanogenesis rather than mere storage. Melano-macrophage centres increase in size or frequency in conditions of environmental stress and have been suggested as reliable biomarkers for water quality in terms of both deoxygenation and iatragenic chemical pollution.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of fish diseases 24 (2001), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Investigation of cranial and spinal deformities in Atlantic salmon smolts from Chile immediately after sea transfer, over two successive crops, demonstrated ankylosis of the mandibular articulation, spinal foreshortening, fracture of vertebrae and rarefaction of osseous and cartilaginous tissues including the operculum. As a result the mouth was permanently agape and opercula could be folded back on themselves. All affected fish had been transferred to sea water at 20 °C plus and fed on particular commercial diets. Fish in cooler areas, or on diets high in vitamin C and phosphorus in the high temperature zone, were clinically normal. The condition has not recurred following dietary adjustment.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 27 (2004), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Phosphorus (P) is an essential component of fish diets. Its deficiency affects not only hard tissues, where it is responsible for rickets, leading to skeletal malformation, but also influences various aspects of intermediary metabolism, and thus growth and feed conversion. Therefore, optimizing the dietary inclusion level is critical at all times. As the aquaculture industry has expanded, so the effects of P in farm effluents, derived from metabolic and uneaten food sources, have also become recognized. Diets are increasingly formulated on a basis that will not only provide adequate P for fish needs, but also endeavour to ensure minimal acceptable P levels in effluents at the same time. Many variables influence P requirements and P availability in fish diets, so it is inadvisable to feed diets formulated to an assumed minimum dietary requirement level, irrespective of the advantages that such a formulation may provide to environmental impact.
    Type of Medium: Electronic Resource
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