Which group of carp species was introduced in the 1970s to control pond algae?

Asian Carp (Bighead, Silver, Grass, and Black Carp).

The specific species responsible for the current ecological crisis are the invasive Asian Carp, which include the Bighead, Silver, Grass, and Black Carp. These fish were intentionally brought into the U.S. during the 1970s, not primarily for human consumption, but for environmental management within aquaculture settings, where they were used to control algae and aquatic weeds in controlled ponds. After these populations breached containment, they spread into major river systems like the Mississippi basin, establishing massive, unchecked populations that now severely impact native fish communities, necessitating the current push for their commercial consumption as a management tool.