It includes posturing, direct attacks and ritualistic displays such as fin flaring and changes of color. During the breeding season some fish protect spawning territories. Fish don't sleep like people, but some fish spend a good portion of their day or night resting. This may reduce competition, conserve energy and keep the fish safe from predators. Fish communicate with one another in many ways.
Senses play a part in communication.
Visual communication is important to most fish. Body movements, postures, colors, color patterns and light are the primary means of visual communication. Sound is also used for communication. Sounds are produced by grinding teeth, rubbing body parts together and with the swim bladder, an air sac inside the body used to regulate buoyancy. Drum, croakers and toadfish get their names from the sounds they produce with their swim bladders.