Indo-Pacific lionfish (Pterois volitans, P.miles complex) were first introduced off the coast of Florida in the 1980s and have become one of the most severe marine fish invaders in the Northwestern Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. Age-specific life history parameters are required for use in models that can be used to determine removal rates needed to effectively manage lionfish densities. This study validated annual increment formation in sagittal otoliths to assess the age and growth of lionfish collected in Aruba in 2014 (n = 44) and the northwestern Gulf of Mexico (NWGoM) in the Flower Garden Banks National Marine Sanctuary (FGBNMS) in 2018 (n = 100). Additionally, Fulton’s condition factor and asymptotic maximum lengths (L¥) were calculated for each of the populations to compare the favorability of environmental conditions and respective growth characteristics. Results suggested that populations were significantly different between the two regions, with lionfish from Aruba exhibiting a greater L¥, growth rate, and greater condition values than lionfish from the NWGoM. It is unclear if these differences were attributable to variability in species composition, or if they in fact, show that lionfish in Aruba have more favorable environmental conditions which resulted faster growth.