The authors have developed methods for obtaining embryos and conducting early life-stage toxicity tests (continuous exposure from the embryonic stage to approximately three weeks or more into the exogenous feeding stage) with three estuarine species of atherinid fishes. Early life-stage tests were conducted for 28-d with Menidia beryllina, M. menidia, and M. peninsulae and the insecticide chlorpyrifos. Responses of the three species were very similar: upper chronic values ('effect' concentrations) ranged from 0.48 to 1.8 micrograms chlorpyrifos/l and lower chronic values ('no effect' concentrations) ranged from 0.28 to 0.75 micrograms/l. Chlopyrifos exposure did not affect survival of embryos to hatching which averaged 91 to 93% for each species. From these three species, toxicologists may select an Atlantic or Gulf Coast species that occurs in either high or low salinity.