ALG-AD partners in France and the UK have been working hard over these last few months to conduct a series of trials, to test microalgae grown on digestate as a fish feed.
In Swansea, the team carried out a trial with Nile tilapia, using hydrolysed Scenedesmus biomass as part of a feed for juvenile fish. In France, the team at CNRS utilised A. mangrovei biomass as a feed ingredient for sea bass juveniles, as well as incorporating hydrolysed biomass in a fish feed for larvae.
Results are currently being analysed, but preliminary data indicate that the survival rates of the fish fed with the experimental microalgae feeds were equivalent to those fed with commercial feed, however growth rate results are mixed.
The objective of these trials was to explore alternatives to fish meal and oil in commercial fish feeds, as there is increasing demand for sustainable aquaculture in North-West Europe, and these fish by-products are often sourced by the exploitation of natural stocks.
The feeds produced by the ALG-AD team utilised microalgae to replace part of the fish meal, and therefore could contribute to a reduction in demand on fish by-products, however, results continue to be analysed to understand whether this would be a feasible option for fish feed producers and other aquaculture stakeholders.