Determination of the acute toxicity of isoniazid to three invasive carp species and rainbow trout in static exposures

Three invasive fishes of considerable concern to aquatic resource managers are the Hypophthalmichthys nobilis (bighead carp),Hypophthalmichthys molitrix (silver carp), and Ctenopharyngodon idella (grass carp), collectively known as Asian carps. There is a need for an effective chemical control agent for Asian carps. Isoniazid was identified as a potential toxicant for grass carp. The selective toxicity of isoniazid to grass carp was verified as a response to an anecdotal report received in 2013. In addition, the toxicity of isoniazid to bighead carp, silver carp, and Oncorhynchus mykiss (rainbow trout) was evaluated. Isoniazid was not toxic to grass carp at the reported anecdotal concentration, which was 13 milligrams per liter. Isoniazid (130 milligrams per liter) was not selectively toxic to bighead carp, silver carp, or grass carp when compared to rainbow trout.