61 



which is done as soon after the absortion of the a 

 possible. In this case the troughs must have all the 

 gravel removed and must be kept scrupulously clean. A 

 very little decayed meat wil) render the water offensive 

 and produce disease. This offensiveness does not show 

 itself in the least in the appearance of the water, which 

 to the eye may be as bright, clean and sparkling as ever. 

 It can, however, be often detected by the smell. When 

 gravel has been for some time in the tanks or troughs 

 where fish are fed even with the utmost care, if a hand- 

 full is taken up it will be found to be very offensive to the 

 olfactories. As well might we expect the human race to be 

 healthy in foul atmosphere, as fish to be healthy in foul 

 water. In the ponds it will sometimes answer to cover 

 up or deoderise the .feculent matter by throwing earth 

 mixed with a very little salt into the water and allowing 

 it to settle ; this not only covers the decaying substan- 

 ces but disinfects them in a measure, on the principle 

 that dry earth is used in the earth closet. The water 

 is to be made quite thick and muddy with the earth, 

 and the operation is to be renewed every few days, as 

 often as necessary. The roiliness of the water does not 

 seem to injure the fish. This, nowever, at best is but a 

 makeshift, and the true plan, especially with young fry 

 is to keep the troughs clean. 



Cleaning the troughs must be peformed daily, in the 

 morning and evening. A thin board nearly as wide as 

 the trough and shaped like a hand shovel, is made with 

 a short stick for a handle nailed across it. When this is 

 held in the water across the trough it creates a strong 

 current under it. It is held in the left hand while in the 

 right hand is a small brush broom such as is used in 

 cleaning sinks, and with which the sides and bottom of 

 the trough are well scrubbed. All the dirt is sucked 



