a male attempted to spawn with the female, the 

 fish were headed in opposite directions. Then 

 he wrapped his tail around her head so that his 

 caudal fin covered her eyes, the end of the tail 

 at times reaching as far as the jxjsterior tip of 

 her operculum. Then the male's body quivered, 

 during which time his pectoral fins beat, but 

 his pelvics remained rather motionless and 

 pointed backwards, and in some cases slightly 

 to the side . The duration of this reflex depended 

 on the female. If she did not react to it, the re- 

 flex of the male was very brief. If the female 

 did not pull away from him immediately or if 

 her avoidance was slow, it lasted about five 

 seconds. Occasionally some prolonged spawn- 

 ing reflexes were observed in which the female 

 was rather passive, and the male discontinued 

 the attempts in about 8 or 10 seconds . When 

 the female responded and participated, the re- 

 flex required about 12 to 20 seconds. 



SPAWNING BEHAVIOR 



sf)erms away from the eggs . However, if the 

 milt was released just before the female lunged 

 forward, her movement would create currents 

 of water that would carry the sperms in the di- 

 rection of the recently released eggs . That such 

 currents of water did occur was evidenced by the 

 fact that the eggs swirled up at the time of re - 

 lease as the female lunged forward. After the 

 lunge, the female remained motionless for a few 

 seconds, her head on the Bottom, her body tipped 

 slightly up and over the egg mass, her caudal 

 peduncle and tail drooped to give her a hump- 

 backed appearance . The male might remain more 

 or less motionless at this time, but he usually 

 became active before the female. When the fe- 

 male began to move again, she usually backed up 

 over the eggs and remained above them with her 

 pelvic fins beating for several minutes. This 

 series of events was then repeated until spawn- 

 ing was completed. 



DURATION OF SPAWNING 



If the female responded, she usually did 

 so within 5 seconds . When she participated she 

 wrapped her tail around the head of the male 

 and quivered in unison with him . Both her pel- 

 vic and pectoral fins were motionless during this 

 act, With each reflex a contraction of the ab- 

 dominal muscles of tfte female moved the eggs 

 posteriorly and progressively produced a flat- 

 tened area behind the pectoral fins . She then 

 lunged forward about 3 to 5 Inches as the eggs 

 spurted out . A current of water, produced by 

 the lunge, caused the eggs to swirl up before 

 they settled to the bottom . 



It was believed that the male released 

 milt at the end of the reflex at the same moment 

 that the female released eggs . However, the 

 reproductive vents in the two fish were not op- 

 posite each other at that time . Since the fish 

 faced in opposite directions, the vents were 

 separated by a distance equal to the distance 

 between the pectoral and pelvic fins. The vents 

 were not brougjit together as in goldfish, carp, 

 and sunflsh, and hence they were further sep- 

 arated by half the width of each fish. The 

 question arose, how efficient fertilizatfon was 

 effected under these conditions . Since the 

 male's pectoral fins beat slowly during the re- 

 flex, the slight current of water which must 

 pass backwards along the male, would carry the 



Of the four spawnings that occurred in the 

 aquariums, we witnessed only one from beginning 

 to end. It lasted 6 hours . Another spawning was 

 estimated to have lasted 6 hours; our calculations 

 were based on the amount of eggs already de- 

 posited when the pair was found spawning . A 

 1 -pound female discharged about three -fourths 

 of her eggs in 3 hours, at which time she was 

 removed and hand stripped. The fourth occurred 

 between 12:30 a.m. and 7:30 a.m. 



The duration of spawning un der natural 

 conditions probably depends on several factors: 

 the size of the female, the intensity of environ- 

 mental stimuli such as lij^t, temperature, or 

 disturbance, and the inherent sexual drive of the 

 participants. In the case of the pituitary-injected 

 fish, the duration probably depended to a large 

 extent upon the degree of hormonal stimulation 

 by the exogenous gonadotropins. However, the 

 fact that all the spawnings required 4 to 6 hours 

 (despite variables in pituitary injections) sug- 

 gested an inherent rhythm . 



NUMBER OF EGGS AND FREQUENCY OF 

 RELEASES 



From 3:30 p.m. to 5:33 p.m., in the 

 case of one spawning, there were 18 depositions 

 of eggs, averaging about 9 each nour. If this rate 



