The sheepshead minnow (Cyprinodon variegatus). an estuarine fish of the Atlantic and Gulf Coasts, is suitable for both partial chronic and chronic (egg-lo-egg) bioassays. The fish is easily held at high population densities in the laboratory and. at about 30 C, produces numerous eggs. The average 3o-day survival of the fish from fertile egg to fry is 75%. Generation time for this species is short (3-4 months) and its small adult size (male average standard Iength=48mm) provides for relatively inexpensive bioassays. This killifish's susceptibility to organochlorine toxicants is similar to that of other estuarine fishes tested and thus should produce significant infonnation on the effects of these toxicants on the estuarine community.