SEEN WITH THE EYE OF A FISH 31 



It is not realised, however, to what extent a fish 

 like the tench reflects the light ; and to illustrate this 

 I placed a tench in an all-glass tank, and, sinking the 

 tank into the pond, I photographed him under three feet 

 of water. The result was a uniformly-shaded dark fish. 

 I then raised the tank and tench to within six inches 

 of the surface, and the black back of the fish now appeared 

 almost white. 



Fish that appear of a uniform shade in the water 

 ;are only protected against a uniform background. Many 

 fish live among rocks, stones, reeds, weeds and other 

 vegetation, and these, in addition to having dark backs 

 and light under -parts, have special markings to assist in 

 their concealment. 



Markings are mainly of two types : spotty or blotchy 

 markings, to make them inconspicuous amongst rocks 

 and stones, and striped markings, to conceal them 

 amongst vegetation. As an example of fish with stone- 

 like markings, let us consider the loach. I show three 

 illustrations of this fish photographed by different lights. 

 In the top illustration the loach is shown perched upon 

 a stone, illuminated by a front light. It was only after 

 considerable difficulty that the fish was persuaded to 

 remain in this unnatural position while I photographed 

 him in order to show the dark back, the white under- 

 surface, and, on the top of this colour arrangement, the 

 special stone markings. He was then allowed to swim 

 off and hide himself, as shown in the middle illustration. 

 But even in this position he was not concealed, for the 



