The Influence of Temperature Variations on Masculinization of Sword Fish (Xiphophours helleri) in Aquarium

This study was carried out in order to survey of temperature changes on masculinization Sword fish (Xiphophours helleri) in Aquarium in aquarium at Natural Resource faculty of Guilan University in 2008. 120 Xiphophours helleri (10- day- old) were evaluated on four treatments (21 ºC، 24 ºC، 27 ºC and 30 ºC) and three repetitions. After six weeks، their sex was determined according to their shapes (prolonging of caudal fins bottom rays، which the name of sword fish was derived from this character). The statistical analysis was done by SPSS، Tukey test and One way ANOVA (P<0. 05). Regarding to the analysis، that was no significant variation in total length and weigth (P<0. 05). The least and most length and weight growth were revealed respectively on treatment 1 (21 ºC، 2. 84cmو 0. 30 gr)، treatment 3 (27 ºC، 2. 98 cm،0. 34 gr)، treatment 2 (24 ºC، 3. 05cm، 0. 33 gr) and treatment 4 (30 cº، 3. 04 cm، 0. 36 gr). During these treatments survey and sex determination CF، BWI and SGR، treatment 1 (21 ºC) showed the significant variation (P<0. 05). The most and least making male percentages were achieved on treatment 4 (30 ºC، 70%) and treatment 1 (21 ºC، 46. 6%).