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The production of silage using fish viscera can be carried out with straightforward methods and permits the exploitation of nutrients that are usually discarded. This process fosters the concept of circular aquaculture. The aim of this study was to evaluate the inclusion of increasing levels of fish viscera silage (VS) on the physical quality of the feed pellets and their effects on their growth performance, health parameters and on economic indices when the experimental extruded feed was offered to tambaqui. A fermented fish VS produced in‐house was included in increasing levels on a wet‐basis in the formulation of five experimental diets (VS 0%, VS 5%; VS 10%; VS 15% and VS 20%). Juvenile tambaqui (~22.6 g) were stocked in fibreglass tanks of 700 L (n = 4; 21 fish per tank) with a recirculation system and the five experimental diets were attributed in a completely randomized design. The fish were fed with the experimental diets (to apparent satiation) for 13 weeks. At the end of the trial, no significant differences were observed for production performance. Fish fed with the highest inclusion level of VS presented the highest concentration of plasma cholesterol, but this was still within acceptable values for this species. The inclusion of fish VS in diets for juvenile tambaqui reduced the activity of the plasma ALT enzyme, confirming normal liver function. Extruded feed containing fish VS had a production cost of US$ 0.95 per kg, which does not significantly impact the economic indices. Up to 20% of fish VS can be included in the extruded feed formulation for juvenile tambaqui without impairing growth performance or affecting health parameters. [ABSTRACT FROM AUTHOR]

The article presents a study to examine blood characteristics of native South American catfish farmed in the Brazilian Pantanal wetland, Sorubim lima. topics discussed include determination of total plasmatic protein, hemoglobin and red blood cell count for the study, staining of basophils with bromophenol blue, Sudan black B and staining of eosinophils with bromophenol blue, and sudanophillic staining observed in granules of eosinophils, basophils and neutrophils of Sorubim lima.

This study evaluated the hematological profile and condition factor (Kn) of tui chub Siphateles bicolor and fathead minnow Pimephales promelas and their associations with larvae of Contracaecum sp. infection of the heart. A total of 30 tui chub and 17 fathead minnow were collected from Upper Klamath Lake, Oregon, USA, measured, and weighed and blood was drawn for hematological analysis. Nematode larvae parasitized tui chub with a prevalence of 50% and mean intensity of 1.40, while 11.8% of fathead minnow were parasitized at a mean intensity of 1.0. Non-parasitized tui chub were significantly larger than the parasitized fish, indicating that small fish could be easily predated by the definitive host, a piscivorous bird. Although the relatively large worm occupied a large portion of the atrium, the presence of the larvae did not affect tui chub Kn, possibly associated with low parasite intensity and a harmonic co-evolution. Only parasitized fathead minnow showed significant differences in red blood cell measurements (greater cell width and larger nuclei) compared to non-parasitized fish. Lymphocytes were the most common white blood cells found in tui chub, followed by neutrophils, monocytes, and periodic acid-Schiff positive granular leukocytes; in fathead minnow lymphocytes were followed by heterophils, monocytes, neutrophils and eosinophils. This study is the first report of Kn and description of blood cells and hematological parameters in these fish species.