86 



especially so in our streams where species 

 of fish are the more numerous. It has 

 greatly limited the growth of most spe- 

 cies beyond an average size, and is in 

 many places responsible for the fact that 

 often a species may become dwarfed in 

 certain bodies of water. In the Salmon 

 river in Idaho it was not an uncommon 

 thing to catch trout of three or four 

 pounds weight. In the smaller tributaries 

 and in the smaller mountain lakes it was 

 unusual to catch one weighing over one- 

 half pound, the average being less than 

 one-fourth pound. I have no doubt that 

 many of those from the small lakes of 

 one-half pound were as old as the large 

 ones taken from the Salmon river. 



Fish eat and grow very irregularly. 

 The average size of individuals, which we 

 would ordinarily call adults, for some 

 species, is different in different bodies of 

 water. Their growth is influenced large- 

 ly by the size and depth of the body" of 

 water in which they live, also by its tem- 

 perature and the amount of suitable food 

 it contains. The value or extent of each 

 of these influences is imperfectly under- 

 stood. 



The forms of fishes are very numerous. 

 Some are extremely long and slender, as 

 many of the species of Eels, Pipe-fishes 

 and the like, while others are extremely 

 short, like Sunfish of the ocean. Others, 

 like the Trunk Fishes, are nearly equal in 

 all dimensions. The average form and 

 the one which best suits our idea of a fish, 

 is the Black Bass, or other fishes of simi- 

 lar pattern. To know the advantages of 

 these forms one must study the fishes in 

 their native element. The peculiar forms 

 Avhich many species take are the most no- 

 ticeable in those found in the tropics. The 

 struggle for existence there is the most 

 severe, and it seems as if each species had 

 labored to take on some peculiar form 

 which would assist most in its preserva- 

 tion. In this respect color also plays an 

 important factor. It is in the tropics and 

 among the many species of corals that we 

 find the most highly-colored fishes. 



Many fishes have the power to change 

 their color, and this they can do in a very 

 short time. The flounders are a peculiar 

 family, the young when born are symmet- 

 rical. Early in life they take on the habit 



of their parents and lie on one side, the 

 eye on the underside disdains to look 

 downwards and so begins to move to- 

 ward the other side. The bones of the 

 head suit themselves to this change and 

 soon our flounder has both eyes on the 

 same side of the head. The upper side is 

 colored much to resemble sand, and the 

 under side becomes nearly white. The 

 flounder protects himself by covering his 

 body, except the eyes, with sand. Flound- 

 ers live on sandy bottoms, some in shal- 

 low water, while others are found in deep- 

 est parts of the ocean. If flounders are 

 placed in an aquarium and arranged so 

 the light can fall on the under side of their 

 bodies, this, too, becomes dark, much like 

 the other side. 



It is interesting to study the habits of 

 fishes in a small aquarium, and to espe- 

 cially notice their ability to change color, 

 and how rapidly they do it. So many 

 persons seem to be saturated with the 

 idea that an aquarium must have in it one 

 or more gold fish. This seems to me to 

 be a mistake when our streams contain so 

 many species suitable for the aquarium 

 which are far more handsome than the 

 gold fish, and which, if you give them 

 half a chance, will teach you something 

 of interest. Mr. Ford, of Berwyn, Illi- 

 nois, has a small aquarium, in his house, 

 in which he keeps from fifteen to twenty- 

 six species of native fishes. Among these 

 are several species of Darters, the most 

 beautifully colored and the most interest- 

 ing of all our fresh-water forms. Then 

 there are Minnows, Suckers, Catfishes, 

 Sunfishes, the Pike, Mud Minnow, Top 

 Minnow, and so on. To one who would 

 know fishes, any one of these species is 

 more desirable than gold fish. The study 

 of fishes in an aquarium, such as the one 

 possessed by Mr. Ford, is extremely in- 

 teresting. They will teach you much 

 about their habits, besides giving you 

 many lessons showing their ability to 

 change color and adapt themselves to 

 their surroundings. 



The BHnd Fishes, which inhabit caves 

 in this country, are very interesting. They 

 have lost their color, if they ever had any, 

 being white. In many the eyes have be- 

 come so degenerated as to be entirely of 

 no service when the fish is in the light. 



