In this study, some of the most important biological characteristics of blackfish (Capoeta capoeta intermedia) from the carp family, which is widely distributed in the catchment area of southern Iran, especially Bushehr province, samples from Shapur river in Saadabad (Bushehr province) from December 2012 to It was caught in December 2013 and studied. Of the 330 fish studied, 197 were female and 133 were male. The longitudinal range of females (total length) from 15 to 29 cm (19.83 2 2.3) and their weight range from 36 to 250 g) 93.4 38 38 (and for males from 15.5 to 26 cm) 19.85 2) Their length and weight were from 36 to 183.27 g) (87.24 9 25.9). The relationship between length and weight of male fish was w = 0.34 / 2.0348 / 34. Total fish obtained w = 0.2L0297 67. Comparison of b values obtained with constant number b = 3 shows isometric growth for females and negative allometric growth for males.Obidity for fish from 0.82 to / 53. 1. The ratio of male to female sex was 0.67 M / F (1) in the caught fish. Egg diameter from at least 406.61 microns in stage 2 of sexual maturation to a maximum of 2112.94 microns in stage 5 of maturation. The mean absolute and relative ovaries were 2252.63 and 22.08, respectively.Historological studies and sexual maturity index (GSI) indicate that spawning is two-stage (March and July) in this fish. No signs of hermaphroditism were observed in black fish.