Critical evaluation of the fathead minnow 7-day static renewal test

Abstract

The practicality and reproducibility of the 7-day fathead minnow static renewal test was evaluated with: 3 preliminary control tests with no chemicals; 4 tests with 2,4-dichlorophenol (DCP); and one test with 1,4-dichlorobenzene (DCB). Overall growth of fish in control tests averaged 0.430 mg ± 0.128 mg per fish (±S.D.; range 0.235 – 0.747 mg), and survival averaged 92.7%. Seven-day tests with DCP indicated the MATC was 3.48 mg/L, compared to a standard 32-day embryo-larval test MATC of 0.795 mg/L. A 7-day test with DCB indicated the MATC was 2.85 mg/L, compared to a standard 32-day embryo-larval test MATC of 0.763 mg/L. A large variation in average fish weight was observed between replicate tanks and replicate tests. Results of these experiments indicate the 7-day test may not provide as sensitive a measure of chronic toxicity as the 32-day embryo-larval test. Further, the prescribed testing and weighing methodology makes the 7-day test quite labor intensive, which minimizes the advantage of the tests short duration.