I was recently asked why I study stream and river fishes. Of course I rattled off several of the high points about threatened habitats, high biodiversity, and simply cool fish. But that question prompted me to reflect on why I do what I do, and I decided to go back to ‘square one’– the well-accepted fish conservation textbook: The Diversity of Fishes: Biology, Evolution, and Ecology by Helfman et al. (2009). In the first chapter, I came across some very interesting numbers, and I used them to make a few infographics that describe the scale and scope of freshwater fish diversity. I’ll let the numbers do the rest of the talking.