HAACK RAISING SALMONOIDS IN INCLOSED WATERS. 681 



not much competition. But he who thinks that pisciculture wil- in a 

 short time make him a rich man had better engage in any other occu- 

 pation, for there is scarcely any branch of human industry which re- 

 quires such constant personal attention and work as pisciculture ! 



But my zeal for a good cause has led me too far from my subject. 



If a locality does not offer a sufficiently large quantity of water ; if 

 there is little or no fall ; if there is no absolute safety from freshets, no 

 extensive establishment should be started, but a more favorable place 

 should be selected, even if the first expense be greater. 



By carefully ascertaining the temperature of the water both during 

 winter and summer, the pisciculturist will know what salmonoids he will 

 be able to raise. 



Saibling can only be raised in places where the water, even during 

 the hottest season, does not reach a temperature higher than + 14° 

 Reaumur (64° Fahr.). A higher temperature, even if the water is changed 

 frequently (G3.50° Fahr.), will kill all the fish. 



I am not able at the present time to say exactly what degree of tem- 

 perature the bastard of trout and saibling can stand, as I have not 

 yet concluded my observations on this subject. But as regards trout — 

 both brook and lake trout — I am prepared to say that they can stand a 

 much higher degree of temperature than is generally supposed. If the 

 change of water does not take place too slowly, trout can live in any 

 river-water. I have already observed that the temperature in ponds 

 has reached 22° to 23° Reaumur (81° to 84° Fahr.) without causing the 

 slightest disadvantage to the trout. During a high temperature the 

 change of water must of course be frequent and rapid. If the tempera- 

 ture is very high the trout is not quite as voracious as otherwise, but 

 does not suffer in any way. 



I must in this connection mention the following fact : 



During last summer I ascertained, by numerous and accurate observa- 

 tions, that our German trout can stand a much higher degree of temper- 

 ature than the American Salmo quinnat, which had been so highly 

 recommended to us on account of its pcwer of resistance to warmth. 

 In three of my ponds the influx of Bliine- water suddenly ceased during 

 the hottest part of summer, because the Bhine-Bhone canal was laid 

 dry. In consequence, all my California salmon died in a very short time, 

 while nearly all my German brook and lake trout remained alive. 



The beginner in pisciculture will see from the above what kinds of 

 salmonoids it will be most profitable to raise. 



It is not the object of the present brief treatise to give exact rules for 

 raising the various salmonoids from the earliest stage of their develop- 

 ment, as this would require more space than is offered by the circulars. 

 I must, therefore, confine myself to a few general hints, hoping that at 

 some future time I may be allowed to enter more into details. 



I, therefore, begin with the treatment of the young fish after they have 

 lost the umbilical bag, i. e., have become able to seek their own food. 



