Is a school of fish considered a community or a population?
As long as all the fish belong to the same species, it would be a population.(population refers to individuals of same species living in the same area at the same time)
However, if the fish belong to more than one species, it would be considered a community.(community refers to different populations living and interacting together)
So, it is population if one species is there, but community if the number of species is more than one.