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DD MMMM YYYY \acceptedDD MMMM YYYYACKNOWLEDGEMENTS
The authors sincerely thank Neil Metcalfe for advice on the design of the trials; Rowan Smith and Phoebe Kaiser-Wilks for assistance with animal husbandry at the Scottish Centre for Ecology and the Natural Environment (SCENE), University of Glasgow; Neil Evans for assistance with sample processing; Samuel-Karl Kämmer and Maria Capstick for laboratory assistance; Martin Kainz for hosting the lipid analyses at WasserCluster Lunz – Biologische Station GmbH; and Garant-Tiernahrung GmbH (Pöchlarn, Austria) for producing and donating fish feed. This work was supported by the Fisheries Society of the British Isles [PhD Studentship to JPK] and the Austrian Science Fund [Stand Alone Project P35515-B to LZ].