A STUDY OF TWIN LAKES, COLORADO. 163 



ditferent kinds of .soil; where certain food elements are lacking in a soil, fertilizers 

 are added, or the soil is inoculated with bacteria which will produce the desired 

 results. In stock feeding- much has been done to determine the relative value and 

 nutritive qualities of the vai"ious kinds of food generally employed, so that this 

 industry ma}^ now be conducted along scientific lines. Comparatively little attention 

 has been given to the food of our useful aquatic animals, however. The whole sub- 

 ject of aquiculture, in fact, has been very much neglected. Analyses have been made 

 and we have been told that our regular food fishes are very nutritious and make an 

 excellent food for us, but our knowledge as to what produces this nutritious food is 

 entirely too limited. The whole question of the relation of quantity and quality of 

 food to the rate of growth and physical well-being of fishes needs much more 

 thorough investigation than it has yet received. 



This neglect of aquiculture is certainly not due to its slight economic impor- 

 tance, or perhaps it would be better to say to small possibilities of its great economic 

 importance. It has been estimated that a bodj' of water of average fertility will 

 produce five times as much as an equal area of average land. Sweeney (1898) calls 

 attention to the fact that a small fish pond (60 by 120 feet) in Indiana produced 1,000 

 pounds of black bass and 2.50 pounds of yellow perch in fifteen months without being 

 supplied with any artificial food. At the price of 8 cents per pound, he estimated 

 that, if the natural waters of Indiana had been relatively onl}' about a tenth as pro- 

 ductive as this pond, the fish products would have been almost equal in value to the 

 corn crop of the state in 1896, the year of this experiment, and a little more than 

 twice the value of the wheat crop. Yet, in spite of the great possibilities of our 

 natural waters from an economic standpoint, most of them receive little or no atten- 

 tion except annually or biennially when our legislators wrestle with the complex 

 problem of devising laws for the protection of fish and aquatic birds. There is little 

 doubt that, if more attention was given to investigations relative to increasing the 

 producing efEciencv of our natural waters, many of the stringent protective laws 

 that now adorn our statute books would become superfluous. 



Like other living organisms, fishes are affected by both the quantity and quality 

 of the food availal)le for them. The (|uantitv of suitable fish food found in a stream 

 or lake determines not only the number of fish that may ])e supported but also 

 the physical condition of those that do survive. When food is scarce, a smaller 

 luimbor will be able to win in the struggle for existence, and those that do win will 

 usuall}" be poor and stunted in their growth. Fish epicures have persistently main- 

 tained that the flavor of a poorly fed fish is much inferior to that of one which has 

 had an abundant supply of food. They also assert that the fiavor is affected very 

 much by the kind of food on which the fish feeds. It is stated, too, that the kind of 

 food affects the growth of a fish very materially. Baird (1857) cites an experiment 

 in which young trout, pi'esumably the same number and of the same size, were placed 

 in three separate tanks and were fed upon different kinds of food. The trout in one 

 tank were supplied with worms; those in another were given live minnows; while 

 those in the third were fed upon " water-flies." The trout which subsisted upon 

 worms grew slowly and had a lean appearance; those which were supplied with live 

 minnows became much larger; " whilst those which had flies alone given to them 

 attained in a short time prodigious dimensions, weighing twice as much as both the 



