NOTES ON THE BREEDING-HABITS OF THE PURPLE-STRIPED GUDGEON, 

 Krefftius adsperstis, Castelnau, 



By ALBERT GALE. 



The purple-striped gudgeons in my aquarium on which the following notes are based are 

 about five inches in length. They have become the parents of between one thousand and two 

 thousand children during the breeding season of 1913-1914. They first bred in 1912, and were 

 then three years old. There was but one spawning in that year, and as a result of it, I have six- 

 teen yearlings from one and a half to two inches in length: these have all the colour markings of 

 the adult fish, though the males are somewhat lighter in colour than the females. 



In October 1913, the colouration of a pair of my gudgeons became intensified, which indica- 

 ted approaching fertility. Accordingly, they were placed in an aquarium which had been prepared 

 fur them during the previous autumn, and judiciously fed, but otherwise undisturbed. The tank 

 was of glass, with perpendicular sides, and measured thirteen by fourteen inches on the surface 

 of the water, which was thirteen inches deep. To make the conditions as natural as possible it 

 was well supplied with water-weeds and pond-snails, and the anchorage for the plants was com- 

 posed of shell-grit, sand, and humus, no clayey matter being introduced. 



Early in the breeding season (15th November), the female deposited her first batch of eggs 

 on the glass side of the aquarium, and others again on the iStli and 27th of December. In the 

 following month, January 1914, she spawned on the 7th, i;'th, and 30th, and now in March she 

 has her tenth lot of eggs. Since last October the male has been tending the various batches of 

 eggs for ninety days. 



The following observations are based on one spawning only, that of Februarv 17th. The de- 

 tails were obtained twice each day, at 9 a.m. and 9 p.m., with occasional intermediate visits. The 

 evening visits were the most instructive, being made by the light of two or three candles placed 

 on the side of the aquarium opposite that on which the eggs were deposited, which clearly 

 illuminated them, as well as the movements of the parent fishes. 



On the 15th and 1 6th. the male made preparations for the deposition of the ova by removing 

 confervoid growths and all foreign matter from the selected site. These he carefully cleared 

 away with his mouth. Meanwhile the female lurked in the weeds on the far side of the aquarium. 

 At 9 a.m. on the 16th, she visited and inspected the site. Approving of it, she placed herself in 

 a horizontal position by it, her abdomen lying at an angle of about forty-five degrees, so that the 

 genital papilla had free play to eject the ova on to the glass. Her position also gave me a clear 

 view of her every movement. When his mate had settled herself, the male drew near, and took 

 up a position about one inch above her. His head pointed in the opposite direction to hers, and 

 his abdomen lay at right angles to the prepared site ; his genital papilla was immediately above 

 that of the female. 



On the morning of February 17th, the first ovum was emitted, and immediately afterwards, 

 two others followed. These were conjoined by a fine hair-like film, and were closely followed 

 by a string of eight. She continued to eject strings of eggs until a circular patch of about two 

 by two inches was covered. All the chains of eggs were placed horizontally, no one crossing an- 

 other, and there were about twenty eggs to the lineal inch. Each egg had a gelatinous base by 

 means of which it adhered to the glass. As the ova were being deposited, the male hovered 

 over the female, it being evident from the movements of his genital papilla that the spermatic 

 fluid was being ejected, and fertilization taking place. 



