ABSTRACT 



Infrared radiation can be used to observe the actions of fish in the dark. Experi- 

 ments demonstrated that the behavior of fingerling silver salmon (O^. kisutch ) was not 

 affected by infrared radiation. The infrared filters used did not pass wavelengths 

 visible to an observer, and the actions of the fish were observed through an infrared 

 viewer. The fish were not attracted or repelled by steady radiation, and they did not 

 exhibit a fright reaction to flashing radiation. The orientation pattern in still or 

 flowing water was not affected; there was no indication that the fish could perceive 

 the wavelengths employed. 



