Fish bodies are streamlined and relatively light so a long fall into water isn't usually a problem. Niagara River expert, Wes Hill, estimates that 90 per cent of fish survive the drop over Niagara Falls. But a waterfall that cascades over rocks, such as Yosemite Falls, will be fatal to all but the smallest fish.

Yes, many species of fish can and do swim down waterfalls, often as part of their natural migration patterns. For smaller fish, the experience is similar to a human going down a water slide; the high volume of water often cushions their fall, and their flexible bodies can withstand the impact. However, the safety of the journey depends on the height of the fall and the depth of the water at the bottom. In 2026, environmental engineers use specialized "bypass" systems or "fish ladders" to help fish navigate man-made dams, but in the wild, species like salmon are known for their resilience in both jumping up small falls and plunging down large ones. Some fish may suffer from "barotrauma" due to rapid pressure changes, or physical injury if they hit rocks, but for many, it is a routine part of moving from upstream spawning grounds to the ocean. Interestingly, some studies show that small fish have a very high survival rate even on falls as high as 100 feet, provided the "plunge pool" at the base is deep enough.