In order to simplify the food chain in a closed ecological recirculating aquaculture system, raw Spirulina platensis cultivated in 50-L photobioreactors were fed to tilapia Oreochromis niloticus as a uni-feed from the onset of exogenous feeding. The feasibility of using tilapia grown on raw Spirulina (body weight: 155.4±3.9 g, standard length: 16.2±0.2 cm; n=3) was investigated for 30 weeks for sashimi (sliced raw meat). Some of the rheological properties of the flesh were measured to clarify the obtained results of sensory evaluations of texture and fatness. The elastic modulus of flesh of the Spirulina-fed fish was significantly higher than that of the control fish (body weight: 168.9±5.8 g, standard length: 17.8±0.5 cm; n=3) that were fed commercial diets. In addition, the viscosity of the flesh of the Spirulina-fed fish was significantly lower than that of the control fish. There was no significant difference in the rupture strength between the two treatments. The rheological parameters in the muscle were found to coincide with the results of the sensory assessment. These results suggest that tilapia fed solely on raw Spirulina have a high flesh quality that is suitable for sashimi. The muscle lipid of the raw Spirulina-fed fish had lower levels of non-polar lipids such as triglycerides and partial glycerides, but higher levels of polar lipids such as phosphatidylcholine and phosphatidylethanolamine. The fatty acid profile of the raw Spirulina-fed fish muscle, especially in the polar lipid fraction, was characterized by an abundance of ∑n-6 highly unsaturated fatty acids (20:3n-6, 20:4n-6, 22:4n-6, 22:5n-6).

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