Fluid preservation in formalin and ethanol is one of the main forms of preservation in modern vertebrate collections around the world. These specimens allow researchers to re-examine specimens in their original form as opposed to skin and skeleton specimens that have been deformed or cleaned of any soft tissues. Stable isotopes are a way to reconstruct an individual's diet, environment, and habits, but researchers typically utilize skeletons and skins avoid the use of fluid preserved specimens because of the unknown effects of fluid preservation on stable isotope compositions. Previous work has focused on the isotope compositions of soft tissues and found that formalin greatly influences the composition. Here, we are evaluating the effects of fluid preservation on bioapatite, collagen, and hair which are relatively stable tissues and readily used in reconstructing ancient ecologies. We have ongoing experiments where specimens were subjected to different fluids (formalin, ethanol, formalin:ethanol mixture) and tissues were sampled over time to record any isotopic changes if they occurred.