Though solitary for most of the year, they form large seasonal aggregations.

In the summer, several groups come together forming larger aggregations.

Group size ranges from 13-36 individuals, and sometimes combining to form aggregations of 50 to 60 individuals.

Rarely, some species form brief aggregations of several hundred animals.

If so, these species are most likely to form dense aggregations that would reduce diversity in local areas.

They are helpless on land, and they sometimes form large aggregations of thousands in surface waters.

At some locations they form large aggregations, though these are not true schools.

They are frequently observed to form aggregations, especially as immature forms, with from tens to perhaps a hundred individuals.

Fish eventually encounter others of their own kind (conspecifics), where they form aggregations and learn to school.

Some species form dense aggregations, either on the sea floor or in the water column, and a small number are subject to commercial fishery.