176 The Development of Modern Fish Culture. 



sideration of the geological formation on which the water lies is 

 of the utmost importance. 



To the casual observer grass is grass and one field is the same 

 as another. The farmer knows that there are very manv grasses 

 with different food values and that some of the most valuable will 

 only thrive on certain .soils. It is precisely the same with regard 

 to aquatic vegetation, and particularly with regard to those most 

 delicate and valuable algte which are necessary to the creatures 

 on which the trout feed. 



In determining what is to be the treatment followed for the 

 impro\'ement of any trout water we have to consider first the 

 nature of the land on which the water lies or over which it flows. 

 After that we must adapt our methods to the natural conditions, 

 making use only of those plants or creatures which experience has 

 taught us are best adapted to this particular locality. 



The geological formation is a most important matter, and we 

 find that in waters which are in a natural state the quality of the 

 trout varies with the value of rock and soil. It may further be 

 said that there is a close parallel between the fertility of land and 

 the productiveness of the water. In practically every case which 

 has come under my observation it has been found that water 

 overlying good fertile land in a prosperous agricultural district 

 produces first-rate trout, while lakes or rivers in barren districts 

 produce poor trout. 



The fish culturist is able to modify the existing conditions, 

 and the means he adopts are very like those employed by the 

 agriculturist, indeed the use of chemical manure has already been 

 proved a success, and they are largely used at our trout farms, 

 and there is little doubt that in the future this principle will be 

 applied to lochs. 



In this work we are greatly helped by the researches of the 

 agriculturist, and, indeed, it may be said that a knowledge of 

 scientific agriculture is essential to the production of the best 

 results from the water. 



