ICHTHYOPHTHIRIUS DISEASE OF FISHES. 5 



consists in removing or destrojdng the large adult parasites after 

 they have dropped off the fish. This may be accomplished by plac- 

 ing the fish in swiftly running water, which carries away the para- 

 sites before they have time to multiply and reinfect the fish. Long 

 troughs or cylindrical tanks can be easily equipped for this purpose. 

 The inside of the receptacle used should be coated with asphalt 

 paint, so that the surface will be smooth and not likely to prevent 

 the parasites from being washed away. The intake must be^ con- 

 structed in such a way as to maintain a steady flow of water through- 

 out the length of the trough. At the overflow the water must be 

 drained off from the bottom as well as the top in order to insure 

 removal of the parasites whether they sink or are carried to the 

 surface of the water. In the case of cylindrical tanks (see fig. 10) 

 the rotation of the water causes the parasites to settle at the center 

 of the tank, where they are immediately carried away. The treat- 



FiG. 10. — Apparatus for the removal of parasites by a continuous fl(nv of water. A, in- 

 take : B, water-spreader for induclug rotary circulation ; C, drain from surface and 

 bottom outlets. 



ment may be made even more positive by scrubbing the trough or 

 tank every day with a strong salt solution after removing the fish. 

 In warm weather infected fish may be cured by this method in 7 to 

 .10 days, and further epidemics can be prevented by quarantining 

 newly brought in stock in this way. Successful treatment in any 

 case depends upon combating the disease when the first symptoms 

 are noticed and continuing it until all the parasites have had a 

 chance to drop from the fish. 



In some instances swiftly flowing brooks or small streams might 

 be utilized by fencing off a suitable section and placing the fish in it 

 until cured. Fish in aquaria can be cured of the parasite, first, by 

 removing all sand and dirt so as to have the bottom of the tank 

 clean ; second, by using about five large tadpoles to each square foot 

 of bottom surface; third, by siphoning off each day all waste ma- 

 terial that settles at the bottom; and, fourth, by adding a level 



