154 GOLDFISH VARIETIES AND 



"Itch," but one can notice small irritated spots, particularly on the tail 

 and fins. The body, however, is not free from attack. The only treatment 

 is to take the fish out of the water and scrape off the pests, for no chemical 

 has been discovered that will cause them to let go, and no doubt if it would 

 it would also kill the fish. 



Fig. 98. Fish Louse (Enlarged four diameters) 



Flukes. The detection of flukes is not easy without the aid of a 

 miscroscope, the cause being a small parasite worm (Gyrodactylus ele- 

 gans), chiefly infesting the gills. The fish breathes unnaturally fast, fre- 

 quently coming to the surface of the water for air. The fins twitch and 

 occasionally the fish will dash wildly and aimlessly about the tank, coming 

 to a rest after exhaustion. Before death the body becomes thin and 

 emaciated. 



If the fish is not too far gone it will stand the formaldehyde treatment, 

 which will usually effect a cure. Place the fish in a solution of 5 drops of 

 formaldehyde to the quart of water. Add one drop per minute (per 

 quart) until there are ten drops to each quart. Allow the fish to remain 

 in this for ten minutes unless it shows signs of 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. 



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

 ent 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 or white worms (described on page 136) 

 they will usually improve rapidly. 



The most common disease among them is Ichthyopthirius, caused by 

 an infusorian parasite burrowing into the skin, producing numberless 

 white raised spots. This requires special and prompt treatment, carried 

 out to the letter as described on page 153. The treatment is worthless 

 unless the 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 by European scientists of 

 the life history of the parasite has evolved the very simple treatment de- 

 scribed, and there is no reason for further serious losses in this direction. 

 This has been proven by the author and other American experimenters. 



