SPAWNING HABITS OF CHROSOMUS. 



15 



may be regarded as the normal spawning behavior of these fishes. 

 All the fishes face up stream, but their swimming movements are 

 only sufficient to keep them from being swept down stream by the 

 current. In the confused and wriggling mass it is difficult to dis- 

 tinguish the movements of individual fishes ; but it may be seen 

 that many males crowd alongside a single female, and those im- 

 mediately in contact with her may occasionally be seen in the 

 spawning position described as occurring in the deep water. 

 Gradually the school crowds closer against the shore, rasping; 



Fig. 5. Spawning grounds of Chrosonius. Spawning fishes crowding up on ihe 

 island of gravel, may be seen near the center of the picture. In the foreground the 

 water is alive with fishes. 



over the pebbles and wriggling into water so shallow that their 

 dorsal surfaces are exposed. In these situations small groups 

 become segregated from the main mass ; their progress is im- 

 peded by the pebbles, so that accurate observation becomes an 

 easy matter. Typically, two males lie alongside a single female ; 

 the group becomes wedged in between large pebbles and in close 

 contact with the bottom, so that the males are enabled to keep 



