What Is a Group of Fish Called?

Fish comprise one of the most abundant and diverse vertebrate groups found across aquatic ecosystems worldwide, from tropical oceans to temperate lakes and ponds. Over 34,000 unique fish species have been identified living in a myriad of marine and freshwater habitats. Many fish species have evolved specialized instinctive behaviors and adaptations over millions of years to help maximize their chances of survival and reproduction.

One nearly universal strategy is forming coordinated social groups of various types and sizes that fulfill key needs. From small schools of neon tetras gliding smoothly together through planted freshwater aquariums to massive shoals of predatory tuna roaming the oceans, specific collective nouns have arisen in English to describe the diverse aggregated groupings created by different fish taxa. Understanding this range of descriptive terminology provides fascinating insight into fish lifestyle ecology, social dynamics, and interaction behaviors.

Reasons Fish Have Evolved to Gather Together in Organized Groups

Fish derive multiple beneficial effects from gathering together with others of their same species in coordinated clusters and communities, including:

Gaining Safety in Numbers Through Predator Confusion

Swimming in close-knit polarized groups of matching fish makes it challenging for predators to isolate and target individual fish in the chaos of constantly moving similar shapes and flashing colors. Safety increases exponentially with greater numbers.

Facilitating Spawning and Reproduction

During breeding seasons, gathering together in large aggregations called spawning assemblies helps fish find mates through pheromonal cues, often with one dominant male presiding over smaller female fish ready to lay eggs.

Enhancing Foraging, Hunting, and Feeding Success

Group hunting concentrates fish efforts in a small area, increasing the likelihood of any individual encountering and catching prey. Pack ambush techniques allow groups to herd and corner prey fish efficiently.

Providing Navigation Support for Vast Migrations

Forming large groups provides orientation, coordination, and energy savings benefits for fish migrating long regional distances to spawning sites by allowing individuals to extract momentum from the currents created by the school.

Diverse Descriptive Names Used for Different Fish Group Types

Various distinctive collective nouns have arisen in English reflecting the diversity of aggregated super-social groupings formed cyclically by fish species worldwide:

School

The most general broad term for a polarized, synchronized group of fish consisting of one particular species all swimming in complete unison is a school. Schools can range from small nuclear units to huge million-member armadas.

Shoal

Also called a herd in some cases, a shoal refers to a more unorganized, random gathering of fish from multiple mixed species swimming together loosely but not necessarily with coordinated or polarized effort.

Shiver

A highly descriptive term uniquely used to characterize a closely clustered group of sharks, derived from their distinctive style of active, shaking cooperative hunting of prey as a pack.

Knot

A especially dense, tightly packed aggregation of fish swimming so close together they appear physically knotted or piled atop one another is aptly called a knot.

Pod

Most often used for marine mammals, pod can also describe a cohesive, close-knit cluster of large migratory fish species such as bluefin tuna, sharks, or oceanic white tip sharks who cooperatively track prey.

Run

A run references a large assembled group of a particular fish species collectively migrating together upstream or along coastlines as one coordinated unit during annual spawning seasons.

Hover

Hover distinctively describes the intimate interaction of a group of seahorses staying within very close proximity and elegantly interacting through intimate synchronized motions and positioning.

Unique Group Names for Certain Fish Species

Beyond general descriptors, some fish taxonomic families worldwide have developed special monikers that reflect their particular lifestyles:

Anchovy – Bait Ball or Bait

Extremely dense spherical bait balls containing up to tens of thousands of individual anchovy fish are referred to simply as bait, due to their vital ecological role attracting predators.

Trout – Hover

A fitting name for a small group of trout holding together hovering steadily in clear shallow riffles and pools is a hover, as they synchronously inspect their surroundings.

Herring – Army

Immense schools of Pacific or Atlantic herring, blanketing many acres while migrating in coordinated battalions numbering up to millions are descriptively dubbed herring armies.

Salmon – Leap

A group of salmon migrating upstream is specifically called a leap when they are observed launching themselves in graceful unison up river rapids, falls, and other vertical obstacles.

Piranha – Shoal

With their signature frenzied cooperative feeding strategy, a ravenous group of Amazonian piranha is most accurately called a shoal, evoking their aggressive swarming behavior.

Perch – Colony

Structurally, groups of bottom-dwelling perch species that cluster densely together over coral reefs, aquatic vegetation, or structure form a colony or settlement, rather than travelling together in polarized schools.

Typical School and Shoal Sizes and Complex Collective Movement Behaviors

The sizes of assembled fish groups and their synchronized collective motions vary greatly depending on species, environment, and functional purpose:

Tightly Coordinated Unison Swimming

Fish within organized schools and shoals precisely match the acceleration, abrupt direction changes, and subtle body positioning of their neighbors, responding in split seconds based on collective intelligence.

Quick Explosive Dashes and Darts

Fast bursts of speed allow groups to defensively evade threats or ambush prey in milliseconds based on collective reaction time and group awareness. Individuals seamlessly follow these rapid erratic movements as an interconnected unit.

Instantaneously Shifting Formations

Fish schools exhibit the unique ability to shift their aggregation patterns and density fluidly from dispersed clouds, to tight spheres, polarized coordinated columns, stacked horizontal layers, or other shapes in seconds as environmental conditions dictate.

Constant Rippling Waves of Motion

Traveling together in schools, fish maintain dynamic flows through the aggregation, rhythmically cascading like a series of synchronized waves flowing through the group that create visually mesmerizing patterns.

Safely Recreating Natural Schooling Groups on a Small Scale in Home Aquariums

While smaller in scope, certain best practices can promote healthy fish schooling and shoaling behaviors even in home aquarium tanks:

Selecting Appropriate Actively Schooling Species

Choose fish species with strong natural schooling instincts like tetras, barbs, danios, small cyprinids, mollies, giant danios, and rasboras over territorial, aggressive, or solitary fish types prone to nip at flowing fins.

Providing a Sufficient Tank Footprint and Volume

Don’t overload the tank, but allow adequate horizontal swimming space and vertical room. Many schooling fish require a 20 gallon long minimum tank volume with added 15-20 gallons per additional fish.

Maintaining Suitable Group Numbers

Keep schooling fish in larger groups of at least six individuals for dynamic interactions, eight to ten for shy timid species, and twelve or more for dwarf species. Odd numbers can help prevent aggressive cliques.

Incorporating Tank Elements that Inspire Activity

Naturalistic plants, rock formations, driftwood obstacles, and open swimming areas help stimulate active schooling and exploration by providing environmental complexity.

Conclusion

From intimate pairs of seahorses to immense oceanic herring spawning armies numbering millions, fish derive countless evolutionary benefits from gathering and living together in coordinated aggregations both large and small.

Observing the diversity of descriptive collective nouns, sizes, synchronized motions, and complex interactive behaviors of the varied fish groupings found across aquatic ecosystems provides fascinating insight into the many ways these streamlined aquatic creatures have adapted social grouping strategies to aid their survival for over 50 million years into the present day.