268 FISH CULTUEE 



the construction of three rows of concrete tanks 

 and two walks; two and a half feet will be a 

 sufficient depth for the tanks, with three feet 

 inside measurement for the width, and four 

 inches will be a sufficient thickness for the con- 

 crete walls. Each tank, which will extend the 

 length of the house, can be divided into sec- 

 tions of varying lengths, from six to twelve or 

 more feet. Both for adornment and utility it 

 would be advisable to have soil on each side of 

 the tanks in which to grow plants that like 

 moist places. An ample discharge-pipe should 

 be set in each section, so that water can be 

 drawn off quickly if desired, and so that con- 

 stant running water can be had in any one sec- 

 tion at a time. A one-inch inflow pipe will 

 furnish plenty of water. 



Outside ponds are important, even where a 

 glass house is used. The commons will live 

 well outside throughout the year, and so will 

 some of the choice Japanese and Chinese 

 types, notably those with scales. Ponds are 

 useful also to hold some of the fish hatched in- 

 side very early in the season, transferring 

 them about May, or when the water-tempera- 



