A very potent general use pesticide found in the roots and stems of several tropical plants. Jewel vine (Derris spp.), Lacepod (Lonchocarpus spp.), and hoary pea (Tephrosia spp.) Are the more common plants from which rotenone is derived. It used in some countries to kill predatory fishes prior to introducing parent fish for natural spawning or newly hatched fry. As an effective fish biocide, rotenone is also used for collecting fish specimens, and in some areas for fishing, where it is added to the water and the dead and dying fishes are collected as they float to the surface. In fishes, rotenone impedes circulation to the gills, causing asphixiation .