BREEDING HABITS OF RAINBOW DARTER. 45 



Spawning may be repeated a number of times before the fish 

 separate. Sometimes during spawning the fish, without separat- 

 ing, move forward along the bottom for short distances. In such 

 cases, or whenever the anchoring of the female has yielded so 

 that she is moved from the bottom by the vigorous activity of the 

 two fish, she leaves the spot where she was lying and again 

 buries herself before spawning is repeated. 



4. Behavior of Two Rival Males toward Each Other. 



Since the fish are crowded into small areas during the season 

 of sexual activity, it is rare for a pair to spawn without a number 

 of males crowding about the female. When a female enters the 

 holding of a brilliant male, several males may attempt to follow 

 her. As one of them approaches, the owner of the holding 

 raises his first dorsal which is a very dark brilliant blue. Often 

 at this warning a small male at once retreats, but if the fish are 

 nearly equal in size and coloration the new comer may stand his 

 ground and also make a display of his colors. With his first 

 dorsal displayed by extending it until its anterior margin rests on 

 his back and points forward, the defender of the holding may 

 then turn on his long axis until his ventral surface is visible to 

 his rival. He thus shows off its dazzling orange and the deep 

 blue of the ventral fins. This attitude is shown in Fig. 1. While 

 he is thus posed the two males frequently move to positions close 

 to the female and parallel with her but on opposite sides. Dur- 

 ing this display the blue of the cheeks and ventral fins frequently 

 flashes out and becomes darker. This momentary intensification 

 of color was more noticeable early in the breeding season than 

 toward its close. 



If the intruder does not retire after this brilliant display he re- 

 ceives a series of blows administered by the defender of the 

 holding who swims at his rival and strikes him repeatedly one 

 fourth to one half inch back of the opercular region. Some- 

 times the blows are given by swimming directly into the oppo- 

 nent and using the head as a weapon, at other times by swim- 

 ming past close beside him and giving a swift stroke of the tail. 

 These combats from all appearances are as harmless as the color 

 display but are in the end always successful in driving away in- 



