Laboratory experiments were conducted to determine the toxicity of Noxfish (an emulsifiable formulation containing 5 percent rotenone) and Pro-Noxfish (an emulsifiable formulation containing 2.5 percent rotenone plus 2.5 percent Sulfoxide as a synergist) to eggs of common carp (CyprinMs carpio) and fathead minnows (Pimephales promelas). Spawning devices were added to brood ponds and examined daily to obtain eggs of known age for testing. The 325 carp eggs were 24 to 48 hours old when treated. Ninety percent of the carp eggs in control containers hatched. The LD.o's obtained for carp eggs at approximately 75° F. were: Noxfish, 0.091 p.p.m., Pro-Noxfish, 0.178 p.p.m. Fathead minnow eggs less than 31 hours old or 101 to 120 hours old were equally susceptible to the poisons. Ninety percent of the fathead minnow eggs in control containers hatched. The LD50's obtained for fathead minnow eggs at 70° to 76° F. were: Noxfish, 0.142 p.p.m.; Pro-Noxfish, 0.233 p.p.m.
