The cavefish it's a type of fish that lives in caves as its name says. Therefore, it has some adaptation that helps to survive in this specific kind of environment. This type of adaptation is called troglomorphism, and it implies evolutionary changes that help the cavefish to reduce the waste of energy developing structures that are not needed for the environment it lives in. Added to blindness (some species sense the environment using specialized cells found in the pineal gland), other characteristics are loss of pigment, energy-efficient swimming because of larger fins, and the loss of swim bladder.