PEOGRESS IX BIOLOGICAL IXQUIEIES, 1921. 21 



awarded a prize by the American Fisheries Society as the most 

 important contribution in the application of biological science to the 

 advancement of fish culture. A series of practical experiments based 

 upon these results Avas conducted during the winter at one of the 

 fish-cultural stations of the Bureau. Just before the close of the 

 year they were transferred to another station where more adequate 

 facilities were available, and it is planned to continue them during 

 the coming fiscal year that definite results may be obtained. 



i^IINXOWS IX RELATION TO FISH CULTURE. 



The smaller members of the minnow family are important to fish 

 culture since they represent a primary source of food for more than 

 20 of the larger food and game fishes. The success of the introduc- 

 tion of game fish into streams or ponds necessarily depends to no 

 small extent upon the suitability of the stream or pond for the sup- 

 port of minnows. Hence the budget of knowledge requisite for 

 efficient fish culture includes information regarding the food and 

 other requirements of minnows. Therefore, while the study of min- 

 nows by C. M. Breder and D. R. Crawford, scientific assistants, was 

 conducted almost entirely outside of office hours and represents a by- 

 product as it were, the results gained are of practical value. 



They studied six common species in the vicinity of the District of 

 Columbia : chub minnow. SenwtUus hullark; red-l)ellied dace, Leucis- 

 CU8 valid orsaJvi; Notropis prorne: shiner or red fin, Notropis cor- 

 nufus; black-nosed dace, Rhinlchfhi/s atranasn.s: cutlip, E .roylosHuni 

 ma,Tillin(ju<i. Ail were found to be predominantly ( arnivorous, in- 

 sects forming the bulk of the food taken, although two species, 

 Notropis proche and E.ro(/losninn jnaxiUiiufun^ consumed much vege- 

 table matter. Various worms, filamentous alga', and diatxmis entered 

 into the food in considerable (juantities. These minnows are, there- 

 fore, in direct competition with the young of important game fish 

 and may even prey upon the fry of them. It is suggested, therefore, 

 that if minnows are introduced into ponds as food for game fish, 

 discretion should be exercised regarding the use of larger and more 

 rapidly growing minnows, sucli as the clnil* minnow and red fin, which 

 may outstrij) young trout in growth and under some circumstances 

 become a menace ratlier than a In^nefit. 



In all ca.ses the suitability of the introduction depends both upon 

 the species of minnow and upon the species of fish which is to be 

 fostered, as well as upon other conditions prevailing in the water and 

 ui)on the degree to which the various factors are under the control 

 of the fish culturist. Minnows seem to thrive best in streams or 

 ponds where the banks bear overhanging vegetation that supports 

 an al)imdan<e of insert life. Wlicrc this condition prevails there is 

 probably less likelihood that the minnows will i)rey upon the eggs 

 or young of other fishes. 



A NEW FORM 01" I'OXD OUTLET. 



Practical success in fish culture depends in no little measure upon 

 economy in construction and operation of the pond and u})on the 

 convenience with which it can be drained for removal of brood stock 

 or young, elimination of enemies, cleaning the bottom, or removing 

 obnoxious plants. The concrete- box outlets commonly used are not 



