The question of whether catfish participate in schooling behavior, similar to herring or tuna, is a common point of confusion for many observers of aquatic life. Catfish species, which are incredibly diverse, generally do not engage in the highly synchronized, coordinated swimming known as true schooling. However, definitively answering this requires understanding the subtle yet important differences in how various fish groups come together. The distinction lies in the temporary, looser nature of their groupings, primarily observed in the younger stages of their lives, contrasting sharply with the solitary habits of mature adults.
True Schooling and Fish Grouping
The collective movement of fish is categorized along a spectrum, ranging from simple gathering to highly organized motion. The broadest term is an aggregation, which describes any group of fish gathered in one area, often due to a shared resource like a food source or shelter, without specific social coordination. This type of grouping can include multiple species and varying sizes of fish.
A more cohesive social grouping is termed shoaling, where fish remain together for social reasons, adjusting their speed and direction in response to their neighbors. Shoaling fish maintain contact and are aware of the group, but their movements are not tightly synchronized, with individuals often swimming independently within the main body of the group.
True schooling, by contrast, is a highly specific, polarized behavior where all individuals move in the same direction, at the same speed, and with uniform spacing. This coordinated movement is maintained through rapid sensory feedback, often involving sight and the lateral line system. It is typically employed by open-water species for hydrodynamic efficiency or predator evasion. Catfish do not exhibit this specific, life-long coordinated motion.
Juvenile Catfish Aggregation
While adult catfish are generally solitary, the young of many common species frequently form dense groups, particularly the fry and fingerlings of Channel Catfish and Blue Catfish. This grouping is best described as an aggregation or a loose shoal, where individuals stay together for immediate survival benefits. These small fish often form a tight cluster when resting during the day or when seeking shelter from bright light.
The primary motivation for this behavior is protection from predation, a concept known as “safety in numbers.” A large cluster can confuse a potential predator, making it difficult to target a single individual. Juvenile Striped Eel Catfish, for example, are known to form dense, ball-shaped aggregations of up to one hundred individuals.
These young catfish aggregations are often facultative, meaning they only come together for specific purposes or under certain conditions. When suddenly disturbed, juvenile Channel Catfish may temporarily form a more organized “flight school” before dispersing again once the perceived threat has passed. This temporary coordination is driven by immediate danger, not a sustained, synchronized lifestyle.
Why Adult Catfish Become Solitary
As catfish grow, a significant behavioral shift occurs, leading them to abandon their juvenile aggregations and adopt a solitary lifestyle. This change is directly related to their increasing body size, which drastically reduces their vulnerability to most predators. A large adult catfish no longer needs the collective defense of a group to ensure its survival.
Most adult catfish, including the large river species, are benthic, meaning they are bottom-dwelling, and primarily nocturnal or crepuscular, becoming most active at dawn and dusk. This ecological niche involves hunting alone under the cover of darkness, reducing the need for visual coordination with other fish. Their solitary ambush or scavenging feeding strategy, often involving probing the substrate with their barbels, is also more efficient when conducted individually rather than in a competing group.
Furthermore, the adult stage introduces reproductive requirements that necessitate solitary or pair behavior. Mature catfish establish specific territories and create nests in secluded spots, such as under logs, banks, or rock crevices, which they then defend aggressively. This territoriality around breeding areas is incompatible with the dense, social grouping seen in their younger years.