Venusian canali occur in low-lying, generally smooth-surfaced plains on Venus and were thought unique because of their great lengths (up to 6800 km) and nearly constant cross-sectional shape. Low-viscosity fluids, widely considered to be rapidly emplaced lavas, which we question, were invoked to have formed the canali. However, we are able to match their key morphological features with modern fluvial and long submarine channels (>3000 km) on Earth; they are therefore not unique to Venus. We also present new evidence for attendant surface erosional processes on Venus. Independent new evidence that Venus's lost water (e.g. oceans) could be stored as hydrous minerals in the crust supports our preferred alternative theory. Despite current hostile conditions at Venus's surface, we are driven to conclude that aqueous fluids may in fact have formed the canali over long periods of time.