WHAT THE FISH SEES 



small amount of light. Under natural conditions 

 it is never absolutely dark in the open. It would 

 be interesting to have fish in absolute darkness and 

 see if they could detect a fly; with bait they might 

 be attracted by the odor. It is known that owls 

 and cats and other nocturnal animals see at night. 

 This is simply a question of a large enough light- 

 gathering surface and sufficiently sensitive retina. 

 It is like the night binoculars used by seamen which 

 gather a large area of the light, thus assisting them 

 to see on dark nights. Beyond dispute, fish have 

 acute vision often far too keen for us poor an- 

 glers. I have often seen them frightened by a 

 leader .004-inch diameter at several feet distance. 

 They see the smallest gnats or midges. I have 

 seen trout rising for flies invisible to me, except 

 in certain lights, when they looked almost like 

 floating dust. Our Maine Indians call these mi- 

 nute midges "No-see-Ums." 



Looking up into the tank through the plate 

 glass you see a segment of a circle within which 

 you can see out to the sky and outer world, and 

 surrounding objects, as explained before, are much 

 flattened when they are near the surface. Beyond 

 this circle you see the reflection of the bottom and 

 objects resting on it. In some of our photographs 



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