' CLEANING SCREENS — ^DISEASES. 41 



put them in so tightly that they cannot extricate them- 

 selves, but will die. In short, wherever yon can run the 

 hig blade of your jack-knife, there the young Trout will 0^0. 

 In making a pond for them, it is best to beat the edges 

 with a spade until they are perfectly smooth, or, better yet, 

 to put a board around the edges to the depth of a foot. 



Cleaning Screens. — If the screens are not kept well 

 cleaned, two ends follow : First, the water runs over the 

 top of the screens instead of through them, and the young 

 Trout will escape ; and second, when the screens are 

 taken out to be cleaned a rush of water follows their re- 

 moval, carrying away with it numbers of Trout into the 

 next pond. "Whenever you are going to clean the screens, 

 drive all the Trout from their vicinity, then take the screens 

 out and wash them with a stiff brush. They can be more 

 easily cleaned by turning the dirty sides downward and 

 knocking them against a stone. Try it once and see how 

 easy it is, and then — don't do it again, if you wish to save 

 your screen. It will be also seen now why it is necessary 

 to have an additional supply running into the second and 

 third pond. A sup])]y of water sufficient lor them would 

 be too much for the first. 



Diseases. — This part of fish-raising is least understood 

 as yet. After the egg sac is absorbed and the fry begin to 

 swim about, a sick one is very easily distinguislied. The 

 healthy Trout swim in the current with their heads up 

 stream, darting about here and there after minute particles 

 of food. The diseased ones wander about listlessly, swim- 

 ming round and round continually. They may also be 

 known by the size of their heads, which appear much 

 larger than their bodies. The head of a young Trout is the 

 largest portion of the fish, even when well, but when sick 

 it appears to be all head. When they are thus affected we 

 4 



