M Sudagar - Department of Aquaculture, Faculty of Fisheries and Environment, University of Agricultural Sciences and Natural Resources, Gorgan, Iran
F Norozi - Department of Aquaculture, Faculty of Fisheries and Environment, University of Agricultural Sciences and Natural Resources, Gorgan, Iran

The swordtail fish is very popular due to its special beauty and sharp, sword-shaped tail, as well as its very good compatibility with peaceful and herbivorous fish. In this research, it will be done to investigate different temperatures on the rate of reproduction and genger in swordtail fish (Xiphophorus helleri). In this research, ۱۸۰ one-month-old swordtail fish (۴۵ males and ۱۳۵ females) were distributed in ۱۵ aquariums with dimensions of ۶۰×۴۰×۳۰ cm, including: ۵ treatments and ۳ repetitions and with the same rearing conditions. Fish in different treatments with Kopens Holland commercial food ۳ times a day and at the rate of ۳% of body weight in treatments (۱, ۲, ۳, ۴ and ۵) which include water in the breeding environment of ۲۲, ۲۴, ۲۶, ۲۸ and ۳۰ degrees centigrade for four months of feeding and at the end of the experiment, the number of larvae born and their gender were measured, the results showed. With increasing temperature, the rate of viability increased from ۲۲ to ۲۸ degrees centigrade, but a significant difference was observed only at ۲۸ degrees centigrade (p≤۰.۰۵). With an increase in temperature from ۲۸ to ۳۰ degrees centigrade, no significant difference was observed in the rate of viability. Also, by examining the gender of the born larvae, the results showed that temperature had no effect on their gender (p≥۰.۰۵).

Temperature, Viability, Sword tail, Xiphophorus helleri