Feeding green: Spirulina ( Arthrospira platensis ) induced changes in production performance and quality of salmonid species

Spirulina is an interesting candidate for fish nutrition. This study aims to investigate the effect of the complete replacement of fishmeal with spirulina (Arthrospira platensis) in the diets of brook trout (Salvelinus fontinalis), rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta fario), in relation to growth and product quality. Two isoenergetic and isonitrogenous experimental diets containing either fishmeal or spirulina as a main source of protein were used for a 10-week feeding trial. Differences in the spirulina acceptance and conversion between species were observed. The experimental diets were well accepted except for brown trout. A species–diet interaction was observed, which led to a reduction in final body weight due to the spirulina supplementation for brook and rainbow trout ((Formula presented.) < 0.05). Parallel, the feed conversion ratio increased to the same extent in the spirulina-fed fish ((Formula presented.) < 0.05), fostering the assumption, that both species did not differ in converting the spirulina diet. Spirulina led to a significant increase ((Formula presented.) < 0.05) in yellow and red coloration in both raw and cooked fillets. The diet had a significant effect on the fatty acid profile, resulting in an increase in SFA and MUFA, while PUFA levels decreased significantly in spirulina-fed fish ((Formula presented.) < 0.05). Overall, total replacement of fishmeal with Spirulina goes along with a reduced production performance and effects on major product quality traits such as fillet colour and fatty acid pattern. In particular, consumer acceptance of the yellow fillet colour should be further investigated. © 2022 The Authors. Aquaculture Research published by John Wiley & Sons Ltd.