Fig. 63. Sea trout brood with Vitelline-sac Dropsy, An accumulation 

 of fluid has formed between inner and outer vitelline sac membranes. 



Fig. 6ii. Graphic representation of the piece loss of rainbow trout 

 in a case of acute inteatinal inflammation. The feeding was 'stopped 

 immediately. The total loss in 10 days was 2600 table trout. The 

 stock consisted of about 38,000 trout, which were kept in JA ponds of 

 100 square meters (1076 square feet) each. 



Variola (Pocks). Sj-mptoms: In carp, hard, white spotted pimples of milk glass-like 

 appearance, in tench, a thin but firm and evenly distributed whitish covering of the skin. 

 They are to be regarded as cancer-like neoplasms of the epidermis. The fins become 

 especially affected and thereby deformed. The causes of the disease can obviously be 

 variable. I disagree with Haempel to regard the disease merely as a case of avitaminosis, 

 and neither is lack of calcium the sole causative factor, I know personally of tv/o fish- 

 eries, especially rich in calcium and continuously exposed to variola. In one of these 

 fisheries, the fish are only occasionally fed, v;hile at the other, the fish are not fed 

 at all. I have also found variola anong non-fed fish in ponds and lakes. 



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