EFFECTS OF CERTAIN METALLIC SALTS 

 UPON FISHES 



By Adrian Thomas, 

 Clark University, Worcester, Mass. 



Contribution from the United States Fisheries Biological Station, 

 Woods Hole, Mass. 1 



It is not the purpose of this paper to give details, but 

 simply to show certain general results which have been 

 obtained during the course of investigation. 



In the experiments upon which this paper is based, the 

 small shore minnow or killie-fish (Fundulus heteroclitus) 

 was used. This is a hardy fish and is plentiful in the wa- 

 ters of the Woods Hole district. Because of the abun- 

 dance and hardiness of Funduli, they are well suited to 

 experimental work. The fact that these fish are killed 

 by certain salts is almost sufficient evidence that any 

 other, more delicate, species would also be destroyed by 

 them, only more rapidly. 



Salts containing nearly all of the heavy metals have 

 been used in the course of these experiments, but only a 

 few will be dealt with in this article. 



Conditions during experimentation were kept as nearly 

 normal as possible in the laboratory. From five to ten 

 fish were placed in battery jars of about two gallons ca- 

 pacity filled with sea water, to which was added sufficient 

 of the salts to give the desired concentration. A con- 

 stant stream of air was passed into the solutions, suffi- 

 cient to supply the amount of oxygen needed, but not 

 enough to super-saturate the media and cause the fish to 

 succumb to "air sickness." The solutions were changed 

 at least every forty-eight hours to insure freedom from 

 products of metabolism, but experiments have shown that 

 the fish would live in a healthy condition even if the wa- 

 ter was changed only once a week, provided that no toxic 

 substances were present. 



1 Published by permission of the Commissioner of Fisheries. 





