New DNA-based research provides compelling evidence that a group of strange-looking fish living near the mouth of the Congo River are evolving due to the intense hydraulics of the river’s rapids and deep canyons. The study, led by scientists at the American Museum of Natural History, the City University of New York, and Fordham University, reveals that fishes in this part of the river live in “neighborhoods” that are separated from one another by the waters’ turbulent flow. In some cases, the researchers found that fishes living less than a mile away from their relatives are actually exchanging very few genes. Many represent distinct species, according to the new study now out in the journal Molecular Ecology.