FOREST, FISH AND GAME COMMISSIONER. 223 



about eight inches high and be swept away. The ponds are generally 

 arranged so that the best and clearest water runs off from above a pond 

 overflow while the foul remains collect in a heap on the bottom. 



As soon as symptoms of the Red Plague are noticed, it is necessary to 

 separate the diseased fish from the others, because the sickness is very con- 

 tagious. If this cannot instantly be done the affected fish must be trans- 

 ferred to clean, swiftly flowing water, by which means part of them can be 

 cured. 



The Scale Disease of the Whitefishes. 



(Lcpidorthosis contagiosa) . 



(Hofcr, Handbuch der Fischkrankheitcn, pp. 9-12). 



The scale disease affects the whitefishes, the various species of Leucis- 

 cidae, such as Dobel (Aitel) Squalius cephalus, Hasel, (Leuciscus vulgaris), 

 Xerfling (Idus mclanotis), Plotzen (Leuciscus rutilus), Rotauge (Scardinius 

 crytlirophthalmus), besides the Brachsen (Abramis brama), Carp (Cyprinus 

 carpio), and many others. 



Up to the present time it is with certainty recognized in the Iser below 

 Munich, in the Spree in the neighborhood of Berlin, in the Rhine in the 

 region of Lundeburg, in Petersburg among fish that were kept in fountains 

 and the disease also has been epidemic among carp in the Kleinhesseloher 

 pond at Munich. Apparently the disease is very widespread, and becomes 

 especially virulent where the water is badly polluted with putrefying organic 

 substances. When this disease is more rarely observed in open waters it 

 simply means that the diseased fish, which here especially lose their activity 

 even being totally paralyzed to the end of the tail, are quickly devoured by 

 predaceous fish and by fish-eating birds. In inclosed ponds the disease can 

 be observed most readily. The market ponds of many fish dealers are the 

 best places in which to discover fish with the scale disease. 



The symptoms of the disease are as follows: On the body of the fish, 

 sometimes for its whole length, more especially on the upper part of the 

 caudal section, the affected scales are raised up so that the body of the fish 

 gives the impression of being swollen or blown up. This raising up of the 

 scales is caused by a clear watery exudation formed in the scale pockets 



