Territorial Behavior

Territory size and defense intensity in fish scale with resource value (food patch richness, nest site quality) and intruder pressure. Farming damselfish actively weed their territories of unpalatable algae species, cultivating a monoculture of preferred filamentous algae — a remarkable form of animal agriculture. Territory defense escalates through a hierarchy of displays: lateral threat posture, fin erection, color intensification, and finally biting. Male Siamese fighting fish (Betta splendens) will fight rivals to exhaustion, making them the subject of extensive research on aggression and contest theory.