ALTHOUGH FRESHWATER ENVIRONMENTS, from creeks to rivers, brim with more than 10,000 species of fish, we may never get the chance to see many of these mysterious creatures as their populations decline. Currently, more than 20 percent of known species are imperiled or already extinct. That’s why David Herasimtschuk doesn’t just photograph fish for fun; he’s a professional photographer dedicated to raising awareness and appreciation of freshwater environments and the wildlife that live in them.

Read more at National Geographic