6 U. S. BUREAU OF FISHERIES. 



tablespoon of salt to each gallon of water about every other day. 

 Goldfish and tadpoles will eat the parasites and by so doing prevent 

 a rapid spread of the disease. 



Nets and siphons used around infected fish should be sterilized 

 each time they are used in a strong brine solution lest the parasites 

 be transferred to other tanks. 



ECONOMIC IMPORTANCE. 



The parasite Ichtlwophthirius has proven fatal to catfish, sunfish, 

 smallmouth black bass, goldfish, buffalofish, trout, bowfin, carp, 

 tench, bream, crappie, white bass, pike perch, pickerel, pike, and 

 whitefish, as well as to many tropical aquarium fishes. Other fresh- 

 water species, such as perch, largemouth black bass, roach, sturgeon, 

 gar pike, and eels seldom are killed by the disease or afi'ected to any 

 noticeable degree. 



At fish farms, aquariums, and hatcheries the disease has often 

 caused a considerable loss of valuable brood stock and fry, the dam- 

 age in many instances amoimting to hundreds of dollars. Fishes 

 that are imprisoned in pools and ponds by the receding of flood 

 waters become infected with this disease and others under the 

 crowded conditions and warm temperatures. The practice of rescu- 

 ing these fish and transferring them to other ponds and aquaria is 

 likely to result in serious epidemics unless the fish are quarantined 

 jind kept under observation for a short time. 



o 



