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 
