3.1 The significance of using chemical fish toxicants is that more complete population analyses or total eradication, or both, can be accomplished. Target species can be selectively eradicated by varying concentrations. This provides a very effective tool in fisheries investigations and management programs. Water conditions (that is, pH, temperature, alkalinity, and so forth) and morphology can be limiting factors.

3.2 Rotenone—Rotenone used as a fish toxicant is highly versatile and can be used effectively to collect fish samples; to eradicate fish; and to selectively remove certain fish species.

3.2.1 Its effectiveness is reduced in cold <20°C, and dosage required increases with alkalinities. It may also eliminate food web organisms. Fish may be repulsed from treated areas.

3.3 Antimycin—Antimycin is versatile in the selective removal of scalefish or even more selectively against certain centrarchids (sunfish) and minnows.

3.3.1 Its effectiveness is reduced in water with pH above 8.5.

1.1 This classification covers rotenone and antimycin which are used to collect or eradicate fish; numerous chemicals have been used but presently only rotenone and antimycin are EPA approved for this use.