100 FISH CULTURE 



poor foundation, it is not feasible to use cement, 

 in which case hollow building-tile is strongly 

 recommended; blocks 24 inches long, 8 inches 

 wide and 6 inches thick may be used success- 

 fully, and will form a wall as durable and 

 attractive as cement. If a pond is only about 

 two or three feet deep the tile can be set in 

 concrete on edge, making a six-inch wall ; when 

 the water is deeper, and the sub-soil very mucky, 

 the tile must be laid sidewise, making an eight- 

 inch wall. Stone is sometimes used for sides, 

 but unless faced with cement it affords hiding 

 places for crayfish, snakes, and other undesir- 

 able creatures, and also refuges for trout when 

 netting a pond. 



Now and then a fish-culturist will advocate 

 covering the bottom of a pond with concrete or 

 boards. I have seen both in hatcheries where 

 fish-culture is conducted on the latest scientific 

 principles. In some I have seen fish doing ap- 

 parently well and in others I have seen them 

 dying by the hundreds. I feel, therefore, that 

 there is enough doubt to make it inadvisable to 

 use either when it can be avoided. There are 

 certain soils where artificial bottoms must be 



