The effects of dietary poly-β-hydroxybutyrate (PHB) on the lipid and fatty acids (FA) in crustaceans were investigated using Artemia as model species. Supplying PHB either in crystalline or amorphous form significantly increased the whole-body lipid contents of starved Artemia. Co-supplying dietary PHB with bacterial PHB degrader Comamonas testosteroni at 106 cells ml−1 for 24 hr also significantly increased this parameter. These findings have important implications on the lipid-saving effects of PHB in crustacean tissues. Dietary PHB, however, did not contribute to the increase in docosahexaenoic acid (DHA) of the naturally DHA-deprived Artemia. Alternative strategy of co-supplying dietary PHB with highly unsaturated fatty acid (HUFA)-rich emulsion for 24 hr effectively improved the nutritional contents of Artemia and at the same time assured efficient delivery of PHB to the larval predator. According to a 13C stable isotope tracer study, the significantly higher δ13C levels measured in Artemia 2 hr postfeeding with 13C-labelled R. eutropha DSM545 indicate that PHB offered in natural matrix is rapidly assimilated. Overall, this study demonstrated the lipid-saving effects of PHB in Artemia. PHB assimilation following gastrointestinal degradation could attribute to its reported beneficial effects in various aquatic farmed species.