Fig. 232. Mollienisia latipinna 



This is one of the most attractive of the fishes from Southeastern United States and 

 Mexico. After many efforts we were fortunate enough to photograph the male in his- 

 courting regalia. The dorsal fin ordinarily is- not so highly raised but appears as in Fig 

 234. The female is of the same species but nearly black in color, a natural freak which 

 occurs once in several million specimens. Breeders have mated black specimens together 

 until now a fairly pure strain of blacks has been established. The young are born alive. 

 Breeding habits, page 242 (No. 18). 



These are principally marine fishes but live fairly well in fresh water. The author 

 suspects they do best in a brackish water aquarium, and that if kept in fresh water they 

 should, every few months, be given the progressive salt treatment described on page 83. 



Most of the live-bearing species mature early and breed before reaching full size, 

 at ages from three to six months. 



Although fertilization takes place in the same general manner as in warm-blooded 

 animals, and the young are developed within the body of the female, still it is not a 

 true process of gestation. There is no connection between the embryo and the circulatory 

 system of the mother. The eggs merely develop and hatch within her body and are 

 dropped when fully formed. The period of development is very variable, depending 

 on the species to some extent, but more upon temperature. We believe the time varies 

 from about six weeks to six months, the shorter time being more usual. It has been 

 noticed that a change of water is liable to bring about a delivery when the young ars 

 about ready to appear, which can be judged by the development of a large dark spot 

 near the vent of the female, as in figures 235, 236 and 239. 



Figures 232 to 241 are all viviparous or live-bearing species. 



253 



