Algae are at the base of the aquatic food chain, producing the food resources that fish are adapted to consume. Previous studies have proven that the inclusion of small amounts (<10% of the diet) of algae in fish feed (aquafeed) resulted in positive effects in growth performance and feed utilisation efficiency. Marine algae have also been shown to possess functional activities, helping in the mediation of lipid metabolism, and therefore are increasingly studied in human and animal nutrition. The aim of this study was to assess the potentials of two commercially available algae derived products (dry algae meal), Verdemin (derived from Ulva ohnoi) and Rosamin (derived from diatom Entomoneis spp.) for their possible inclusion into diet of Atlantic Salmon (Salmo salar). Fish performances, feed efficiency, lipid metabolism and final product quality were assessed to investigated the potential of the two algae products (in isolation at two inclusion levels, 2.5% and 5%, or in combination), in experimental diets specifically formulated with low fish meal and fish oil content. The results indicate that inclusion of algae product Verdemin and Rosamin at level of 2.5 and 5.0% did not cause any major positive, nor negative, effect in Atlantic Salmon growth and feed efficiency. An increase in the omega-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) content in whole body of fish fed 5% Rosamin was observed.

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Interest in the potential to both farm and wild-harvest seaweeds in Australia is rapidly increasing. Seaweeds are rich sources of dietary trace minerals and essential elements that are often not found in terrestrial edible plant foods. Due to the high affinity for mineral and contaminant accumulation by seaweeds, it is important to conduct in depth studies on seaweeds that have edible potential and are being considered for sustainable aquaculture or wild harvest. This study screened six Australian fucoid and laminarian brown seaweeds for their dietary mineral composition. Spatial replicate samples of each species were collected from three ‘clean’ Victorian sites (classified based on their proximity to urbanisation and potential pollution sources) and processed with methods consistent for human consumption. Dried and ground samples were analysed by ICP-MS and concentrations of 12 key dietary minerals were compared amongst species. The overall dietary mineral composition differed significantly amongst all species, except between two species in the Sargassaceae; but concentrations of individual dietary minerals varied amongst species in complex ways. Results are discussed in the context of the potential health benefits from consuming the species studied in realistic quantities (e.g. 10 g·d-1 dried seaweed) as part of balanced omnivorous and plant-based diets. This study demonstrated high levels of dietary minerals essential for optimal human health in the Australian brown seaweeds investigated, but further investigation into ways to reduce iodine content in some species may be required to maximise health benefits from regular consumption.