Fish jumping out of water is a common and often captivating behavior. This aquatic phenomenon serves various purposes, from immediate survival responses to actions driven by biological imperatives. Fish may leap for reasons linked to their interaction with their environment or their internal state.
Avoiding Hazards
Fish often jump to escape immediate threats, including predators or undesirable water conditions.
Fish frequently jump to elude predators like larger fish, birds, or other hunting animals. This sudden, acrobatic maneuver can disorient a pursuing predator, providing a momentary escape advantage. Smaller fish, vulnerable to many predators, often use quick leaps as defense. Game fish, like marlin or largemouth bass, might also jump to dislodge a fishing hook. Invasive species like Asian carp jump high in response to vibrations, such as from boat motors, which they may perceive as a large predator.
Unfavorable water conditions can also prompt fish to jump. When water quality deteriorates (e.g., low oxygen, extreme temperatures, or high pollutants), fish may jump to find more suitable conditions. This behavior can also signal irritation from poor water chemistry.
Seeking Opportunities
Beyond escaping danger, fish jump proactively to gain advantage, access resources, or navigate their habitat. These jumps are often strategic actions related to feeding or migration.
Some fish launch themselves from the water to capture prey above the surface, including low-flying insects or small birds. For instance, the silver arowana, a South American fish, can leap to catch varied prey like birds, bats, and snakes. Giant trevally fish have been observed snatching fledgling terns from the air.
Jumping is also crucial for migratory fish to navigate river obstacles. Salmon, for example, are known for powerful leaps over waterfalls and rapids to reach their upstream spawning grounds. This allows them to continue their journey to reproduce in natal streams. Some fish might also jump to move between connected bodies of water or access new feeding grounds.
Responding to Physiological Needs
Fish jumping can also stem from internal biological processes or discomfort. These reasons are often less obvious but rooted in the fish’s physiological state.
During mating and spawning, jumping can be part of courtship rituals or competitive displays. Female fish may jump to help loosen their eggs, while males might jump as a show of strength or to release milt.
Fish may jump to dislodge external parasites or irritants from their skin or gills. The impact of hitting the water’s surface can help remove these unwanted organisms. This “flashing” behavior is a common response to parasitic infestations.
Jumping can also be a generalized response to stress, illness, or agitation. Fish experiencing discomfort from disease, injury, or overcrowding may exhibit erratic swimming, including jumping, as a sign of distress. This behavior indicates a general malaise rather than escape from a specific external threat.