Taste and Smell
Just as in humans, taste and smell are closely connected in fish. In fact, they’re so closely related that it’s better to bunch them together under the title "chemoreception." Fish use these senses to locate food and to communicate by means of receptors concentrated in the mouth, nasal openings, and around the head. Some species have receptors spread over their body or concentrated in barbels (whiskers) around the mouth for use in low light, such as catfish and loaches.
Since water conducts electricity, some fishes can use a low-level electric field to detect changes in their vicinity. They generate this field by emitting pulses from an organ near the tail and pick up changes with sensory receptors near the head or by using their lateral line. Using this system, they can detect fish moving nearby, solid obstructions in the water or food in low-light conditions. Electroreception is also used to navigate when light is scarce.
Image: bensonkua / via Flickr
Term used to refer to animals that have a spine or backbone, including fish and mammals
Moving or located away from the midline; located along the side