What do you call a group of fish swimming together?

A group of fish swimming together is called a school. The word describes fish moving as a coordinated group, often matching one another’s direction and speed.

Biologists distinguish between shoaling and schooling. Fish are shoaling when they gather for social reasons, even if they swim independently. They are schooling when they move in a highly organised, synchronised formation. In everyday English, however, “school” is the standard answer for a group of fish.

Swimming together can help fish detect predators, reduce an individual fish’s chance of being attacked, find food and locate mates. Some fish may also gain swimming efficiency by taking advantage of the water movement created by nearby fish.

The other options describe groups of different animals: a flock is usually birds, a herd commonly refers to hoofed mammals, and a pack often means dogs, wolves or other social carnivores. “Shoal” is a related term, but “school” is the most familiar answer for fish swimming together.