986 BULI^ETIN OF THE BUREAU OF FISHERIES. 



discussing the subject of degeneration, and many astonishing facts have been 

 brought out. Good eggs are cheap even at 5 crowns (or $1), and a breeding 

 estabHshment can be maintained properly and on a businesshke footing only 

 when the eggs bring 10 crowns. At present the fishes are bred down into a 

 wretched condition. The much desired eggs from America will degenerate in 

 the same way if the method of breeding for reproduction is not henceforth differ- 

 ent from that which has prevailed. 



The unfavorable conditions surrounding the American trouts in this country, 

 brought to my knowledge through experience during the long period I have men- 

 tioned, I have found to be due partly to inadequate insight into many essentials 

 of fish culture, and partly also to things which could not be changed. I have 

 been able, however, to acquaint m3^self with some of the phenomena of degenera- 

 tion and their causes, and some of them I have successfully combated. 



I consider the principal causes of degeneration to be : 



1 . Unhealthy pond bottom, i. e. , bottom on which ooze and remnants of food 

 as well as excretions accumulate for months at a time. The slower the current 

 and the longer required for the water to run off, the more dangerous grow the 

 conditions even at a low temperature of from 10° to 1 3° centigrade. The planting 

 of water cress on the bottom and the introduction of carps and perches is not suffi- 

 cient by any means, as these fish do not wallow in the ooze at temperatures of 10° to 

 13°. For example: A spring pond having an area of 140 square meters and a 

 depth of from 60 to 100 centimeters was stocked about the end of August with 

 1,500 rainbow trout of the same year, and disease appeared in January, 1897; 

 it was impossible to drain the basin without lowering the level of the water in 

 the principal pond and disturbing the entire establishment. The ooze was 

 taken out by means of a strong pump and a rubber hose; in some places it was 

 black and bad smelling. The disease disappeared entirely a few days later. 

 After this I succeeded in saving the one-year-old fishes in low-water ponds with 

 weak currents by means of frequent pumping out of the ooze and by keeping the 

 bottom clean. 



2. Substitutes for the natural food. Fresh flesh of fishes (I had only fresh- 

 water fishes) must be considered as natural by the effect produced, even if it is 

 cooked. I never succeeded in keeping the trout healthy for a long period when 

 using substitutes (a mixture of fresh blood cooked with shrimp meal, or the 

 spawn of sea fishes, or fish meal — Ideal brand — and flour as a binding material) 

 without an abundant addition of fresh fish. Within two and at the latest within 

 three months there were traces of change of color to a darker, dimmer hue with a 

 bluish tinge, more noticeable in the many-colored brook than in the darker rain- 

 bow trout. If they reached the blackish-hue stage they could not be saved. In 

 such cases live natural food without any adulteration proved the best of remedies. 



