304 FISH HAICHERV MANAGEMENT 



the pectoral fins. The caudal fin may be completely destroyed. A peduncle 

 disease lesion usually starts on the caudal peduncle behind the adipose fin, 

 where it causes inflammation, swelling, and gradual erosion. The disease 

 progresses posteriorly and the caudal fin may be eroded. Coho and chum 

 salmon are the most susceptible and, in sac fry, the yolk sac may be 

 ruptured. 



Peduncle disease or coldwater disease is caused by a flexibacterium, 

 Cytophaga psychrophilia. The bacteria are water-borne and can be transmit- 

 ted from carrier fish in the water supply. Crowded conditions stimulate a 

 disease outbreak but are not necessary for the disease to appear. 



The best treatment for peduncle disease is the oral administration of 

 drugs with food. Sulfasoxazole (Gantrisin) and sulfamethazine (not reg- 

 istered by the Food and Drug Administration), at 9 grams per 100 pounds 

 fish per day, or oxytetracycline (Terramycin), at 2.5 grams per 100 pounds 

 of fish per day, should be given for 10-14 days. Chemotherapy combined 

 with, or followed by, external disinfection with Roccal will give better and 

 longer lasting results. 



FIN ROT 



Advanced cases of fin rot can resemble peduncle disease, but in this disease 

 bacteria are found in fin lesions only and no specific type of bacterium is 

 recognized as its cause. Signs may occur incidentally in the course of 

 another bacterial disease, such as furunculosis. In typical fin rot, fins first 

 become opaque at the margins and then lesions move progressively toward 

 the base. Fins become thickened because of proliferation of tissue and, in 

 advanced cases, may become so frayed that the rays protrude. The entire 

 caudal fin may be lost, followed by a gradual erosion of the peduncle. 



Common water bacteria such as Aeromonas hydrophila and Pseudomonas sp. 

 often are found in lesions of fin rot. Flexibacteria sometimes are mixed 

 with other types of bacteria. The disease is associated with poor sanitary 

 conditions that lead to fin abrasion, secondary bacterial infection, and fi- 

 nally fin rot. 



The best results from treatments of fin rot infections are obtained with a 

 soluble form of Terramycin added to water at 10 to 50 parts per million for 

 1 hour. Control also may be achieved with Hyamine or Roccal (not re- 

 gistered by the Food and Drug Administration) in a concentration of 1 to 2 

 parts per million for 1 hour. 



FURUNCULOSIS 



Fish furunculosis, a septicemic disease principally of salmonids, has been 

 known since 1894. It was first reported in the United States in 1902 and, 

 since then, virtually all trout and salmon hatcheries have either been 



