ACUTE ORAL TOXICITY OF 1,496 CHEMICALS 

 FORCE -FED TO CARP 



By 



Howard A . Loeb 

 Senior Aquatic Biologist 



and 



William H. Kelly 

 Conservation Biologist 



The carp ( Gyprlnus carpio ), introduced 

 into North America in the nineteenth century, 

 has become so undesirably numerous in many 

 waters as to suggest control for the best in- 

 terests of game fish resources or best water 

 quality. For the most part the areas concerned 

 are large so that complete eradication of carp 

 would be very difficult, and the destruction of 

 other fish by nonselective chemical treatment 

 would make this method dangerous and costly. 

 Research on selective methods of chemical con- 

 trol seems desirable. The selective feeding 

 habits of carp are favorable to the development 

 of a poison bait technique. A preliminary step 

 toward development of such a technique has 

 been the screening of large numbers of chem- 

 icals for their effect on carp when force -fed 

 to fish held in large aquariums at the Fish 

 Laboratory at DeBruce (near Livingston Manor, 

 N.Y.). 



Precedent for the discovery of a suitable 

 poison to be incorporated into bait for carp has 

 been established by the development of many 

 chemical pest control devices . Hundreds of 

 chemicals are now used extensively against 

 such pests as insects, mites, nematodes, and 

 rodents. Most of them are nonselective, i.e., 

 they act against many besides the target species. 

 Development of safer, selective poisons has 

 been difficult. 



The subject of toxicity, selective or 

 otherwise, is very large and involves all life 



forms from viruses to the larger species of 

 animals and plants. A vast and growing liter- 

 ature encompasses efforts in the medical and 

 agricultural fields, but this is not true of fish- 

 eries, where chemical work has been relatively 

 limited. 



Nevertheless, several extensive screen- 

 ing programs have been carried out as, for 

 example, the attempt to find chemicals that 

 would selectively kill oyster enemies and the 

 successful efforts to find a selective chemical 

 that would act at certain levels only against sea 

 lamprey larvae (Applegate et al, 1957). In 

 addition, a number of insecticides have been 

 employed successfully in fishery work, and 

 these have largely been general in effect. 



The screening method of search for 

 effective compounds is often the most practical 

 available today, but in the future chemicals may 

 be discovered in a more efficient manner, as 

 outlined by Adams (1959): "Comparative bio- 

 chemistry is, of all branches of science, the 

 one that holds the master key for logical dis- 

 covery of selective toxic agents . It can reveal 

 metabolic differences between the economic 

 species which man wishes to save and the un- 

 economic species which he wishes to destroy. 

 Once these metabolic peculiarities are dis- 

 covered the next step is to devise selective 

 agents which can use them to cause irreparable 

 damage to the uneconomic species. Unfortu- 

 nately, comparative biochemistry has so far 



This report is a contribution of Federal Aid in Fish and Wildlife Restoration Project F-9-R 



