738 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



my last report, and referred to more at length under the heading be- 

 low, which carried off a great many of the breeding trout; and the 

 second was a terrible rain-storm which visited the McCloud Eiver in 

 December, 1885, just before the trout began to spawn, and which forced 

 so much mud and sand into the ponds that many fish died from the 

 effects of earthy matter collecting in their gills. Specimens of trout 

 that died of the disease and of some that died of earthy matter in their 

 gills were sent to Prof. S. A. Forbes, of Illinois, for examination. 



Some brief memoranda, which are given in Table YI from Mr. Green's 

 diary, contain information in regard to the weather, the trout fishing, 

 and other matters, from September 7, 1885, to December 31, 188G. 

 Table Y is also added, showing the temperatures of air and water at the 

 station between the same dates. 



Disease affecting rainbow trout. — Mr. Green, superintendent 

 of the trout ponds at the McCloud Eiver station, described a disease 

 which affected the rainbow trout in the ponds and river at this station 

 during the fall of 1885, and caused the death of many breeding fish, 

 substantially as follows : * 



The fish all died in the same way, being apparently in perfect health 

 up to the time of their being taken with this disease, while none that 

 were taken ever recovered. By watching them closely, the first symp- 

 tom discovered is that the fish begin to grow dark colored, some of them 

 nearly black, and about the second day after this they refuse food and 

 seem inclined to keep very quiet, and remain most of the time resting 

 on their left sides at the bottom of the pond. This symptom differs 

 from any I have ever witnessed in trout before. I have seen a great 

 many fall sick and die, some from old age, others from bruises or fun- 

 gus or other causes, but they almost invariably rise near the surface, 

 and sometimes so near the top that their back fins will be out of water, 

 and as they grow weaker they keep falling off towards the back screens; 

 but such is not the case Avith any of these fish dying of this disease, as 

 they lie on the bottom all day long unless disturbed, while if disturbed 

 they swim off apparently all right. If taken from the water they seem 

 to shake or quiver, and will splash around quite lively for a moment. 

 They remain in this state from three to six days, breathing very natur- 

 ally. I have kept them seven days after this, always lying on their 

 sides and breathing faster each day. They seem to be in no pain, but 

 simply stupefied. I think they would live even longer than this if it 

 was not for the sediment that gathers in their gills from their being so 

 quiet in the water. Some of them seem to cramp and their bodies will 

 be crooked and it is almost impossible to straighten them. I have given 

 them earth, salt, and everything I could think of as remedies, but to no 

 avail. After they stop breathing it is eight or ten hours before they 

 begin to get stiff or look like dead fish, and I have opened them forty - 



* For previous references to this disease see F. C. Report for 1885, p. 134, and F. C. 

 Bulletin for 1885, p. 472. 



