20 ANIMAL LIFE UNDER WATER 



doubt that the same colour schemes and mark- 

 ings that conceal life under the water from man 

 conceal it also from fish. In support of this 

 statement I must explain that when I first 

 started to watch the habits of fish in observation 

 ponds, one particular species was examined at a 

 time. A month or more before these were intro- 

 duced into the pond it was prepared so as to 

 resemble the usual habitat of the particular fish 

 to be observed, not only as to water supply and 

 vegetation, but also with regard to its natural 

 food. When I decided to examine the brown 

 trout, gravel, stones and rocks were arranged on 

 the bottom of the concrete pond. A watercress 

 bed was planted at the shallow end where the 

 water flowed in, and the pond was stocked from 

 an adjacent stream with fresh-water shrimps, 

 snails, caddis, stone loach and minnows. 



When the balance of life was established and 

 the shrimps were breeding freely, a wild trout 

 from the same stream was added to the pond. 



A constant stream of water ran through the 

 observation pond, and the clear space in front 

 of the observation chamber was virtually a pool 

 in a trout stream. 



When visitors descended into the chamber 



