What Is Fish Shoaling?

Shoals are groups of fish that not only swim together, but exhibit collective behavior characterized by polarization and synchronization in their movement. One of the fascinating aspects of schools is the level of organization they present. Each shoal is made up of individuals that are very similar to each other, meaning that it is rare to find specimens of different sizes or ages within the same shoal group. This uniformity contributes to harmony and efficiency in the movement of the school.

Species known to form schools include sardines, anchovies, herring, tuna and several types of sharks. An example of a shark that shoals is the scalloped hammerhead (Sphyrna lewini). These can be particularly terrifying if we see a shoal of sharks together since they combine their resources for hunting. Fish shoaling is facilitated by physical and behavioral adaptations that allow them to participate in the collective behavior of the school effectively.

While shoaling can help fish to navigate their ecosystem, this does not mean that cannot do so on their own. Learn more with our article on whether sharks are blind.

Establishing a group of fish in the form of a shoal has numerous benefits for the species that carry out this behavior. This is because forming a large group of fish brings a number of advantages. Among these benefits, the main highlights are protection against predators and more efficient foraging in feeding areas.

Some of the benefits to fish that are provided by shoaling include:

• Protection from predators: fish that move in groups have a greater ability to confuse and deter predators. Shoals create a larger, more confusing visual and acoustic picture, making it difficult for individual predators to focus on a specific fish.
• Foraging efficiency: shoaling allows fish to track and find food sources more efficiently. By moving in groups, fish can take advantage of signals and cues provided by other members of the school to locate and capture prey.
• Improved reproduction: they play an important role for many species of fish. By grouping together, fish increase their chances of finding and attracting reproductive partners. Schools create a greater concentration of breeding individuals in a specific area, facilitating the encounter between males and females in the process.
• Temperature regulation: just as gregarious mammals will huddle together to conserve their warmth, fish can do the same when shoaling. By swimming in such close proximity, they can better conserve their heat in cold waters.

It is important to know that the shoal dynamic in fish helps with survival, but there are likely reasons for the collective behavior which we are yet to determine. Fish can use the shoal to teach the individual members behaviors which can help with their survival, something that is best learned together. Further study is required for us to know all the lessons they may be learning.

Before starting to differentiate between a shoal vs. a school of fish, we will first know the definition of each individual concept:

• Shoal of fish: compact and cohesive group of fish that move and act together in the water. Fish within a shoal generally maintain a relative distance from each other and move in a coordinated manner. Shoals can be made up of a single species of fish or several species grouped together.
• School of fish: considerable concentration or aggregation of fish in a specific area. It may be a gathering or collective of fish of different species that congregate in a certain area due to the availability of food, favorable environmental conditions or the presence of other attractive factors.

Now that we have learned about the concepts of shoal vs. school of fish, it will be easier for us to recognize the differences between the two. Such differences include:

• Coordination and behavior: in a shoal, fish exhibit collective behavior in which they follow coordinated movement patterns. In contrast, fish in schools tend to move more independently and do not necessarily follow a coherent movement pattern with other fish in the group.
• Size and density: a shoal may consist of a limited number of individuals of one or several species, while a school of fish tends to be a larger, more dispersed congregation involving a larger number of individuals.
• Functions and benefits: shoaling fish generally serve specific functions and benefits, such as protection from predators, foraging and reproduction. In comparison, schools of fish can form as a result of foraging in areas with abundant resources or as refuge in areas that offer favorable conditions.

Now that you know more about the nature of shoaling in fish, you may also be interested in our related articles which explain types of piscivorous animals and what is overfishing?

If you want to read similar articles to What Is Fish Shoaling?, we recommend you visit our Wild animals category.