ON THE FOOD OF FISH. 117 



to think that this insect has, as I have said, much 

 to do with the iineness of the fish ; and the more 

 so, because, -wherever I have found it to exist in 

 any quantity, I have invariably observed that 

 the trout are of fine size, and in unusually good 

 condition.^ 



In lakes, also, it is a very common thing to find 

 the trout in one lake large, bright, and weU fed, and 



* These inaects of course thrive better in sluggish than in rapid 

 water, though they do well enough in either when there are weeds. 

 They are peculiarly well-adapted for lakes ; and were I owner of a 

 lake, I would leave no stone unturned to introduce them in large 

 numbers. They feed upon almost anything, and are the scavengers 

 of the water. They are very fond of the large fresh-water mussel, 

 and destroy and eat them in large numbers. These, which are 

 easily introduced, should be as food for the trout food. Where the 

 streams are too rapid for the plentiful production of the gam- 

 mari, it would be by no means a bad plan to make here and there 

 (where the situation of the soil and the banks suited such a plan) 

 small shallow ponds, supplied with water by means of a small pipe, 

 and having an exit to the stream. In these the requisite kind of 

 weeds might be planted, a stock of these little insects turned in, 

 and some kind of offal or other food occasionally being cast to 

 them, and the insects left to thrive and increase. They would of 

 their own accord make their way into the stream, where they would 

 afford excellent food for the trout. Other kinds of insects might 

 be also placed in such food-breeding ponds, where they might 

 propagate and multiply in safety. By such a method as this almost 

 any amount of the food best suited to the trout might no doubt 

 easily be produced. For if we increase the stock of fish, we must, of 

 cowrse, if their size and weight is to be kept «p, grow food for them 

 somehow, and this seems not to be a very difficult plan. 



