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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI:

    Diet-induced nephrocalcinosis in aquarium-raised juvenile spotted wolffish Anarhichas minor

    Karine Béland, Catherine Rousseau, Stéphane Lair*

    *Corresponding author:

    ABSTRACT: Wolffish are regularly housed in aquaria, but little data on their husbandry and health is available for care takers. High occurrence rates of nephrocalcinosis and urolithiasis have been observed in Atlantic Anarhichas lupus and spotted A. minor wolffish housed at 2 Canadian zoological institutions. To explore the effect of diet on nephrocalcinosis and urolithiasis development, a 16-month prospective study was conducted. Thirty-two juvenile spotted wolffish were randomly assigned to 4 experimental groups fed exclusively with the following diet: (1) Skretting® Europa 18 pellets; (2) Mazuri® LS Aquatic Carni-Blend Diet Formula; (3) Vitamin-supplemented fish-based diet, and (4) Vitamin-supplemented invertebrate-based diet. Urinalysis, radiographs, and complete necropsies were performed at the end of the study. None of the wolffish developed uroliths during the study period. All the specimens fed with the fish-based and invertebrate-based diets developed nephrocalcinosis, whereas this condition was seen in 12.5%, and 0% of the fish in the Skretting® and Mazuri® groups respectively. Affected wolffish often presented with oxalate crystalluria, and increased radiodensity of the posterior kidneys. Urinalysis and radiographic study were considered useful in the antemortem diagnosis of nephrocalcinosis. None of the previously published risk factors for the development of nephrocalcinosis in fish were supported by the results of this study. However, nutritional analyses of the 4 diets suggest that high dietary levels of gelatin or vitamin C or low levels of vitamin E could be potential risk factors for the development of nephrocalcinosis in spotted wolffish and thus warrant further study.