DISEASES, PARASITES, AND PROBLEMS 47 



Malachite green and copper sulphate are most com- 

 monly used as fungicides. For fishes, a copper sul- 

 phate dip of 1:2,000 for 1 to 2 minutes or a malachite 

 green dip of 1:15,000 for 10 to 30 seconds is recom- 

 mended. For the treatment of eggs, Burrows (1949) 

 recommends an hour-long treatment of malachite 

 green at 1:200,000 twice weekly. 



Bacterial Diseases 



As pointed out above, it is frequently not practi- 

 cal to positively identify bacterial pathogens. The 

 matter is further complicated by the fact that all of the 

 bacterial pathogens of fishes have not been thoroughly 

 investigated and there exists some confusion as to the 

 number of organisms involved. Further, little is 

 known concerning the susceptibiHty of di£Ferent 

 species of fishes to the different pathogens. Despite 

 these problems it is still of value to outhne the com- 

 monly recognized bacterial diseases. The reader is also 

 referred to the following important review papers: 

 Griffin (1954), Snieszko (1954), and Rucker et at 

 (1953). 



Furunculosis, caused by the bacterium Aeromonas 

 salmonicida, has been rather thoroughly studied. The 

 salmonid fishes are especially susceptible to it, al- 

 though it is also suspected of infecting warm water 

 fishes. The bacterium is a short, nonmotile, gram nega- 

 tive rod that shows bipolar staining. Host symptoms 

 include bursting of capillaries, resulting in red spots, 

 reddening at the base of the fins and a bloody fluid 

 from the gut. Septicemia is usual, the kidneys are 

 swollen, and furuncules may or may not develop. Sul- 

 famerizine at the rate of 8-10 grams per 100 lbs. of 

 feed is recommended as chemical treatment. A. saU 



