For signals over large distances, fish essentially rely on hearing alone. Vision Most fish have very well developed eyes. Vision underwater is affected by light, water clarity, distance, contrast and size of object. Olfaction - the sense of smell Smells and odours spread much more slowly through water than do light or pressure fields. The chemicals that cause them also linger much longer in the water than they do in air.
Fish have nares that are the organ of olfaction.
They also may have taste buds at several locations on their body in addition to in their mouth. Most of the fish's sensory responses can be modelled. These responses can also be incorporated into more complex models that include other aspects of fish behaviour.