Abstract: 8921 A. Introduction

The fathead minnow (Pimephales promelas Rafinesque) is a small, common, and widely distributed freshwater fish of the family Cyprinidae. This minnow is maintained easily in the laboratory and can be spawned year-round. These attributes have led to its widespread use in aquatic toxicology studies, particularly those using early life stages (i.e., embryos and larvae), such as the short-term tests for measuring the chronic toxicity of effluents.

Other procedures for testing larval growth of fathead minnows are available.¹