FISH DISEASES 161 



exhaustion sooner. Return to a thoroughly disinfected tank and 

 repeat the operation next day. Two or three treatments will usually 

 be sufficient. As a rule, all the fishes in a tank are affected, so if this 

 parasite is positively identified, it will be well to treat every fish that 

 has been exposed. 



We can see no reason why the formaldehyde treatment should not 

 be applied to any of the parasitic ailments. If carefully used it will 

 at least cause no trouble. 



Ichthyopthirius. This parasite causes small whitish dots all over 

 the fish. It is more apt to affect tropical fishes and has killed many 

 fine specimens. Until recently it has been considered incurable, but 

 two cures are now positively known. The fish should be placed in 

 a plain glass or enamel container and have the water changed (keep- 

 ing temperature even) every eight hours, disinfecting container each 

 time. It is best to use two containers, so the water can stand in one 

 while the other is in use. This takes a few days. It is claimed that 

 plain water is as good as salt for this treatment, but the writer has had 

 better success with brackish water, gradually increasing the strength 

 and then as gradually reducing. 



The second method of treatment is only suited to goldfishes. This 

 consists of treatment in water in which two grains to the gallon of per- 

 manganate of potash have been dissolved. In a few days the old 

 mucous coating of the fish peels off and leaves a new, healthy surface. 



Diseases of Tropical Fishes. Tropical fishes cannot stand the dif- 

 ferent chemicals and treatments recommended for goldfishes. The 

 principal cause for their lack of condition is too low a temperature. 

 If placed in a uniform warmer temperature, with one ounce of sea 

 salt to each gallon of water, and fed up on daphnia, small chopped 

 earthworms, or white worms (described on page 140), they will 

 usually improve rapidly. 



The most common disease among them is Ichthyopthirius, 

 described above. The treatment is worthless unless changes of water 

 are made on time. Aside from chill this epidemic kills more tropical 

 fishes than any other cause. It has long been considered incurable, 

 but recent careful study of the life history of the parasite has evolved 

 the very simple treatment described and there is no reason for further 

 serious losses in this direction. This has been fully proven by the 

 author and has been amply attested by the uniform success of many 

 readers of former editions of this work. 



