6 . WHOLESOME WATER NECESSARY. 



from the banks of streams, to such a distance that the 

 leaves cannot fall into its waters, as the decomposition of 

 arboraceous matter produces humic acid gas, which is 

 always prejudicial, and in some cases, when in excess, is 

 destructive to all kinds of fish, as it interrupts their feeding 

 and suppresses their growth. This will serve to account 

 for the extraordinary fact, that, in private ponds exposed to 

 these injurious influences, the fish have not increased in 

 weight during many years. Wholesome water is "of as 

 much importance to fish as pure air to man ; and as impure 

 air affects his health, so does impure water affect the finny 

 tribe, and render them sickly and small. The depletion of 

 our rivers is due, not so much to the disturbing traffic of 

 steam-vessels, shipping, or any other river and river-side 

 movements, as to the increase of our population, and the 

 consequent increase of the refuse matters of towns and 

 cities : for to this is to be ascribed the impure state of 

 most of our fresh-water streams, as they are called by 

 courtesy a courtesy too complimentary. Strange to say, 

 however, the very cause of destruction to the fish while in 

 embryo produces them abundance of food when once 

 brought into life. For instance, the very mud or alluvial 

 deposit in our rivers and streams, which is an enemy to the 

 embryo, breeds such myriads of worms, larvae and insects, 

 that when the young fish all dangers overcome find 

 their way into it at last, they have no labour to procure 



