NATURALIZATION OF AMERICAN FISHES IN AUSTRIAN WATERS. 



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By FRANZ VON PIRKO, 

 President oj the Imperial and Royal A ustrian Fishery Society 



In the belief that it might greatly interest American fish breeders to know 

 what experiences and observations have been made by Austrian pisciculturists 

 in regard to fish imported from America for breeding purposes, and in compliance 

 with a special invitation from the committee of the Fourth International Fishery 

 Congress, Washington, 1908, the Imperial and Royal Austrian Fishery Society 

 has called upon the prominent fish breeders to furnish their observations regard- 

 ing the results obtained with such American fish. These results, which are 

 briefly set forth here, warrant the conclusion that of all the Salmonidse which 

 can be taken into account for breeding purposes the American rainbow trout 

 must be regarded as the most important. This trout, which has now been in 

 Austrian waters for a quarter of a century, despite manifold opposition has 

 gained, so to say, the rights of citizenship there. Owing to its excellent qualities 

 it has been quickly introduced into all pond fisheries and is really a first-class 

 salmonid. In consequence of its ability to endure deep water, the number of 

 ponds in which it can grow is quite considerable, and pond-fish owners would be 

 well advised to allow plenty of room for the rainbow trout, without forgetting, 

 however, that after all it is a salmonid. Its capacity to stand high temperatures 

 enables it to replace the pike in carp ponds, the more so as it does not possess 

 the dangerous qualities of the latter. 



The irideus is just as indifferent to high temperatures as to cold. Therefore 

 at a time when the Salmo fontinalis, or brook char, and the native brook trout have 

 long ceased to take food the irideus still comes to its meals, and the advantage 

 offered to the breeder by its appetite, displayed even when the pond is covered with 

 ice, must not be underestimated. In addition to this its power of resistance 

 against diseases is amazing. It is not only — perhaps owing to its perceptibly 

 thicker skin — far less exposed to the attacks of the malignant Saprolegniaceae 

 than all the other Salmonidse, and therefore very rarely seized with fungus, but 

 it also appears to possess immunity from the most dangerous bacterial diseases, 

 such as furunculosis. Its indifference to polluted waters enables it to live in water 



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