Linear regression analyses were performed on weights and lengths of larval fathead minnows in an attempt to evaluate these variables as comparable measures of the growth endpoint in short-term chronic assays. Mean dry weight and mean individual total lengths were highly and positively correlated (R values of 0.82 - 0.98) for data generated from seven-day fathead minnow larval survival and growth tests performed on effluents from a variety of treatment facilities (industrial, municipal, and refinery). Length measurements were also found to be accurate, precise, and capable of detecting the same level of significant differences between control and treatment means. In comparison to weight measurements, substantial time can be saved using larval lengths obtained with a very simple setup and cost of equipment can be reduced as well. Length measurements should be considered as an alternative to the mean dry weights presently required by EPA Method 1000.0.Natural Scienc
