Salinity can impose physiological challenges on freshwater fish, forcing them to prioritize osmoregulation over other processes such as growth. Our study aims to assess how varying salinity concentrations in streams affect fish growth and diet. We expect that fish living in higher salinity will exhibit lower growth (smaller otolith sizes), because energy is redirected to osmoregulation rather than somatic development. We hypothesize that fish diets will contain a lower richness of invertebrates at higher salinities due to reduced foraging efforts or changes in prey availability. To test these hypotheses, we collected Northern Plains Killifish (Fundulus kansae) and Fathead Minnows (Pimephales promelas) in prairie streams across Wyoming that ranged from 486 to 23,500 µS/cm in salinity and 7.2 to 9.21 in pH. We compared stomach contents to available invertebrates to assess selection. The otoliths were extracted, measured, and analyzed for annuli growth patterns to estimate annual growth rates. Fathead Minnows exhibited reduced energy allocation toward growth when exposed to elevated salinity and pH (p-values: 0.0006, 0.0054). In contrast, Northern Plains Killifish growth was unaffected by increased salinity (p-value: 0.6922) but was influenced by higher pH (p-value: 0.0381). Both species experienced a simplification in diet composition. To further investigate energetic trade-offs, food availability will be compared to consumption to determine the proportion of intake. These findings suggest that under high salinity conditions, energy is likely being redirected toward osmoregulation rather than growth. Our findings provide valuable insights for fisheries management to understand how increasing salinity can alter fish. Increasing concentrations of salt is particularly concerning in arid regions like the western US, where salinity concentrations are predicted to rise due to climate change and other anthropogenic factors. Understanding that fish change their diet and their growth is slowed is critical to developing adaptive management strategies to sustain aquatic ecosystems in the future.