196 THE TROUT 



admit light without depriving the fry of the benefit 

 of the sheltering shade afforded by the other half 

 which remains closed. At night both sides of the 

 lid are always closed, and a padlock is an excellent 

 safeguard if there is any fear of 'the fingers of 

 meddling boys.' During periods of severe frost it 

 may be necessary to protect all the boxes by covering 

 them with planks. The rearing boxes will want daily 

 cleaning with syphon and brush. Some kinds of food 

 cause more deposit than others, but with so many 

 mouths to feed in such a small place, unless your 

 cleaning work is done every morning with regularity 

 and thoroughness, the result will be tainted and un- 

 wholesome water, no matter what food you may use. 

 When this has happened a heavy penalty is likely to 

 await you for your failure to ensure cleanliness. You 

 will have left open the gates of your citadel to the 

 great enemy fungus, or to some foe even more insi- 

 dious and almost equally destructive. 



A distressing feature of some of the worst maladies 

 of the young trout is that the effect of them does not 

 always make itself manifest immediately; and you 

 may be living in a fool's paradise, all unaware of the 

 presence of the enemy in your midst. Particularly so 

 is it with certain affections which attack the gills, the 

 fishes' lungs. The gill-covers conceal the ravages of 



