During the first and second years and until the fish is about 14. centimeters long, 

 the brovvn trout wears the so-called juvenile coat. It consists of from 10 to 13 large, 

 oval black spots upon the sies (see Fig. 70). Tfiiile very sililar to young salmon, at 

 that stage, the brovm trout is recognizable by 5 smaller black spots upon the rear gills 

 covers. Young salmon have only two such spots and ver;."- large ones. 



Some scientists, and especially Englishmen and Norwegians like Kyle and Ehrenbaum 

 see in lake, sea and brovm trout only different representatives of one and the same 

 species. Brown trout and lake trout have presumably evolved from the sea trout (as 

 evidenced already by their Latin labels). Proof for this hypothesis is seen in the fact 

 that sea trout, raised in fresh water acquire the characteristics of brown trout. 

 Marked brown trout, planted in the Baltic Sea revert back, in appearance and growth, to 

 sea trout. It is also presumed that after the glacial period sea trout evolved from 

 the brown trout. 



From the exclusively natiiral presence of the brook trout as suggested in a "Trout 

 Brook" occurring in the uppermost region near the source of flowing streams of the 

 central mountain zone as well as of the plain, the trout is a fish which has a com- 

 paratively small power and latitude of adaptation. It embodies the "Stenotype" in 

 contrast to the pike, which on account of its greater power of adaptation is a 

 "Eurytype". 



Fig. 22. Brook Trout (Brown Trout). 

 16 cm. length fish, not artificially fed, from a large pond. 



The trout favors cool waters and does not tolerate great changes in temperature 

 ("Stenothermic" cold v;ater animal). Trout also like clean v;ater with a "through current" 

 or "through flow" (reophil). They favor oxygen and are sensitive to pronounced fluctu- 

 ations in the oxygen rate of the water "stenooxyybiontic" , Cornelius has demonstrated 

 that brown trout assimilate natural food better and artificial food less well than rain- 

 hoyi trout. 



These especial environmental demands are the reason that brown trout Is more diffi- 

 cult to domenticate than rainbow trout. 



On the other hand, one should not underestimate the assimilative possibilities of 

 brown trout, as shown by the possibility of a brown trout to become a sea trout. But 

 the trout must becone accustomed to changed environmental conditions at an early stage 

 in life in order to thrive and to subsist, 



I have raised especially large fingerlings in the carp ponds at Eberswalde, for 

 instance, from self-feeding brood. The ponds were 50 to 100 centimeters deep, the 

 water temperature (in Llay and June) constantly 20 degrees centigrade and later on, on 

 the airfaoe, repeatedly as high as 28 degrees. The fingerlings from these ponds in the 



94 



