Abstract: Aquatic and wetland associated plants have been helping traditional medicine systems across South and Southeast Asia, sub–Saharan Africa, and Latin America, for generations, but their phytochemical as well as antioxidant capabilities are still way less systematically mapped than those of terrestrial medicinal plants. Here we gather reported lab results from six species that have clear medicinal credibility and a real aquatic or semi aquatic home: sacred lotus (Nelumbonucifera), water hyacinth (Eichhorniacrassipes), water spinach (Ipomoea aquatica), blue red water lily (Nymphaea nouchali), Indian pennywort (Centellaasiatica) and the cyanobacterium Spirulina platensis. For each one, the reported total phenolic content (TPC), total flavonoid content (TFC), and DPPH/ABTS radical scavenging IC50 figures are taken from the original articles and set side by side, along with the qualitative phytochemical categories that were identified within each species. Looking across all six, phenolic plus flavonoid levels track quite broadly with how strong the free radical scavenging looks, which fits the standard hydrogen atom transfer, and also single electron transfer explanations used for polyphenolic antioxidants. The reviewed work further hints at uses that go beyond human phytomedicine, like using water spinach, and even algal biomass, in aquafeed mixes to help reduce oxidative stress in fish that are raised on farms. Still, there are fairly big inconsistencies between studies: extraction solvent choices, which plant part was sampled, and how the assay was run. Those issues make direct comparisons between species difficult, and they are addressed here, plus future routes for more standardized research are outlined.