DISEASES AND ENE:^^ES. 63 



colder by contact with the air. If the water is so shig- 

 gish as to be likely to rise above sixty-eight degrees in 

 summer, the ponds may be shaded in some way. Trees 

 and bushes look very nicely about the borders of the ponds, 

 and are valuable so far as ornament is concerned. But 

 there are certain objections to their use which will banish 

 them pretty thoroughly from the grounds of the practical 

 Trout-raiser. One objection is tliat the leaves, in autumn 

 especially, clog up the screens, and demand constant atten- 

 tion to prevent an overflow of the water and Trout. Or 

 the leaves fall to the bottom of the pond, and decaying 

 there, foul the pond. The roots of the trees also will force 

 their way towards the water, and break the walls or banks 

 of the pond. If it is necessary to shade the ponds, floats 

 may be used, made of boards nailed together and moored 

 in some convenient place ; but the best plan of shading is 

 by light covefs placed on beams running across the pond. 

 If the ponds are very large, the floats w^ill have to be used. 

 But the ponds must not be made large. We have said that 

 Trout would not live in water which was raised above 

 the temperature ot sixty-eiglit degrees, and would do better 

 in water at forty degrees. This settles the question as to 

 how far south the Trout will live. It will live as far south 

 as the temperature of the water in summer will allow. 

 As to the exact latitude that depends upon elevation, &c. ; 

 but there are few Trout, if any, to be found in the South- 

 ern States. 



Diseases and Enemies. — The diseases to which adult 

 Trout are subject are very little understood. At least the 

 cause of the diseases and their remedies. Sometimes a 

 Trout will be observed to have a white fungus growing 

 upon it in spots. This will spread over the fish until it 

 dies. Sometimes the fish will turn to a black color. 

 This always seems to be an indication of blindness, as we 



