The Fishes of an Acid Lake

The water of Vincent Lake, Cheboygan County, Mich., had a hydrogen ion concentration of pH 4.4 with a dissolved oxygen content of 5.58 to 6.46 c.c. per liter. The acidity of the lake is probably due to the boggy character of a part of its margin. Four species of fish, Perca flavescens, Ameiurus nebulosis, Lepomis incisor, and Esox lucius, were found in the lake, the first three species occurring in considerable numbers. No molluscs whatever were found in the lake. Conclusions as to the optimum hydrogen ion concentration for any species of fish based upon behavior experiments, must be held in reserve until the behavior of fish from a large variety of habitats has been investigated.