424 U. S, BUREAU OF FISHERIES 



ciency of improved methods in the handhng of brood fish, care of 

 ponds, and in combating the fish diseases which have been prevalent 

 at the Neosho station for a long period. 



Neosho {Mo.) station. — -During a very protracted spawning season 

 of the rainbow" trout, extending from November 12 to January 23, 

 slightly m.ore than 1,000,000 eggs w^ere obtained from the 1,280 

 2-year-old and 3-ycar-old female lish on hand. The usual low percent- 

 age of fertility was apparent among the eggs, although there was an 

 improvement along this line amounting to 10 per cent over last sea- 

 son's egg collections, very nearly 64 per cent of the eggs taken produc- 

 ing fry. 



There was an increased amount of disease among the fingerling 

 trout, the most serious trouble being diagnosed as crystals in the 

 kidneys, a condition which the superintendent believes to be due to 

 an inlierited predisposition. During May an epidemic of gyrodactylus 

 was readily checked by dipping the affected fishes in a cider-vinegar 

 solution. Later in the season ichthyophthirius also became mildly 

 epidemic but was soon eliminated by increasing the flow of water 

 and lowering its level, thereby increasing the current throughout the 

 infected ponds. To gain some further knowledge of the cause of the 

 disease diagnosed as crystals in the kidneys and a possible remedy 

 therefor, it is purposed during the next few years to discard all brood 

 fish after their first spawning. This policy will at least have the 

 advantage of providing a larger number of adult fish for stocking 

 local waters, and quite possibly it may result in gaining some infor- 

 mation of practical value to fish culture. 



The principal articles of diet for the fish during the year were fresh 

 meats, largely beef heart, though considerable quantities of hog heart 

 and sheep liver were also used. Clabbered milk in small quantities 

 was employed occasionally to vary the diet and as a corrective 

 measure in digestive disorders. The station superintendent expresses 

 faith in the value of the milk in this connection. 



No effort was made to obtain rainbow-trout eggs from the Roaring 

 River field station during the year. After carefull}* noting the con- 

 ditions at this point for four months prior to the spawning season it 

 appeared certain that the field could not be advantageously worked. 

 This decision was later substantiated by the low yield of fertile eggs 

 obtained by the owner of the plant, the percentage being less than 10. 



The distribution of brook trout was confined to a small number of 

 fish that had been transferred earlier in the year from the Man- 

 chester (Iowa) station. From a small number of brood brook trout 

 held in the station ponds during a portion of the year eggs of such 

 inferior quality were obtained that the entire lot, together with the 

 fish, was discarded as being of no value in practical fish culture. 



Notwithstanding the fact that the floods occurring during the 

 spawning season of 1923 interfered materially with the fish-cultural 

 work, the number of fingerling bass and other pondfishes produced 

 was over 100 per cent larger than in the previous year and was well 

 above the general station average. One of the main difTiculties 

 encountered in the propagation of pondfishes at the Neosho station 

 has been the innumerable parasites with which the brood fish soon 

 become infested. In the late fall of 1923 practically all the brood 

 fish were disposed of and the pond inclosures allowed to remain bare 

 throughout the winter. At the present time all the ponds, w^ith the 



