Fish are one of the most diverse groups of vertebrates on Earth. They can be found in every single type of environment, from freshwater to salt water and even deep sea trenches. Fish have a variety of adaptations that allow them to live in these different habitats, but do all fish see equally well? Some people believe that because they spend so much time underwater and only come up for air at night, fish might not need good vision since there is little light down there.
Some fish can see well in the dark, while others have a better sense of smell. Still other fish use their fins to “feel” around them for food and obstacles that might be there. It is hard to say what all types of vision are like underwater since so little research has been done on this topic.
The best way to determine if an individual species’ eyesight would depend on how they spend most of their time-on land or underwater. But just because you may not be able to see something doesn’t mean it’s not there! If things move quickly enough, some animals (including people) can still detect motion with only one eye open even without any light available at all.