Most fish possess highly developed sense organs. Nearly all daylight fish have colour vision that is at least as good as a human's (see vision in fish). Many fish also have chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears, many fish may not hear very well. Most fish have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey.[1] Sharks can sense frequencies in the range of 25 to 50 Hz through their lateral line.[2]
Fish orient themselves using landmarks and may use mental maps based on multiple landmarks or symbols. Fish behavior in mazes reveals that they possess spatial memory and visual discrimination.[3]