Experiments to determine the relationship between plankton production and fish production were conducted in a series of small, excavated ponds. The ponds were stocked with bluegill bream in May, and received four applications of inorganic fertilizers during the season. Water samples were taken from each pond every two weeks for quantitative and qualitative plankton determinations. The ponds were drained in November and the number and weight of fish from each were recorded. The data indicated that a direct relationship existed between plankton production and fish production.

A heavy production of plankton (76.1 p.p.m. of organic matter) formed a heavy scum of decaying organic matter on the surface of one pond on June 26. One-year-old fish died in this pond due to insufficient oxygen (the minimum concentration was 0.1 p.p.m.). Fry in the same pond survived.