Invasive crayfish are a significant threat to freshwater biodiversity across the globe. Invasive crayfish often have plastic traits that enable them to persist in new environments– one such plastic trait may be metabolic rate. Estimating the standard metabolic rate (SMR) and routine metabolic rate (RMR) of invasives compared to natives allows for direct comparison of energy expenditure for survival at rest and under basic activity, respectively. Alabama has the highest diversity of crayfish species in the world, and includes some invasive crayfish. In central Alabama, the Cahaba River watershed has been invaded by Faxonius virilis, and in southern Alabama, the Conecuh River watershed has been invaded by Procambarus clarkii. Here we determined if there are differences in SMR between invasive and native crayfishes in both systems. We estimated SMR and RMR for two native and one invasive species from the Cahaba and in the Conecuh using intermittent-flow respirometry equipped with fiber optic dissolved oxygen (DO) sensors and automated data loggers. We compared F. virilis to Cambarus coosae and Faxonius erichsonianus within the Cahaba watershed and compared P. clarkii to P. acutissimus and P. versutus within the Conecuh watershed. All crayfish were kept in individual artificial freshwater holding tanks under a 12-hr light/dark cycle for a minimum of two weeks. DO readings from respirometry trials were converted to rates of consumption (MO2 values), corrected for background respiration. SMR was estimated for each individual by determining the 20th percentile MO2 during a 10-hour period of lowest respiration. RMR was measured as the median MO2 during light cycle and dark cycle for each individual. We used 8-10 individuals of each species to estimate SMR and RMR. Preliminary data suggest that SMR and RMR are lower for invasive as compared to native crayfish, suggesting a lower metabolic cost for invasive crayfish. Lower SMR and RMR, and presumably metabolic needs, may be a species trait that can predict successful invasion, particularly in association with other demonstrated traits of successful invaders, such as elevated growth, fecundity and aggression.