Reproductive biology of two sympatric species of tooth-carps: Aphanius hormuzensis and Aphanius furcatus, from south of Iran (Teleostei: Aphaniidae)

Some aspects of the reproductive biology of two endemic tooth-carps, Aphanius hormuzensis and A. furcatus, from southern Iran, were studied by regular monthly collections throughout one year. Significant differences were observed between the total number of females and males, females being more abundant. Based on the pattern of reproductive indices including the gonado-somatic index and Dobriyal Index, it was concluded that these fishes spawn in April and May. The estimated absolute fecundity of A. hormuzensis ranged from 78 (TL = 32.2 mm) to 730 (TL = 51.1 mm), with a mean value of 219.78±66.50 oocytes per fish based on 15 females. The relative fecundity ranged from 68.45 to 518.54 oocytes/g body mass (Mean±S.D: 237.67±96.87 oocytes/g). For A. furcatus, the estimated absolute fecundity ranged from 53 (TL = 26.9 mm) to 102 (TL = 32.04 mm), with a mean value of 93.73±45.37 oocytes per fish based on 15 females. The relative fecundity ranged from 22.41 to 123.65 oocytes/g body mass (Mean±S.D: 64.98±23.37 oocytes/g). Due to overlapping of spawning season in these two sympatric species, it seems that other pre- and post-zygotic factors are responsible for absence of natural hybrids in the studies tooth-carps in the Mehran River.