International Journal of Biology Reports

fa Gonad histology and some reproductive parameters of the big mouth Lotak, Cyprinion macrostomum (Cyprinidae) in the Little Zab River, Tigris River drainage, Iran تخصصي Special پژوهشي Research The reproductive characteristics of Cyprinion macrostomum in the Little Zab River, Iran, were investigated by monthly collections from November 2021 to September 2022. A total of 175 specimens were collected and transferred to the laboratory, where biometric measurements were performed. For the histological studies, the gonads were fixed in 10% buffered formalin, hydrated, and embedded in paraffin. They were then sectioned transversely at a thickness of 5-7 μm and stained with Hematoxylin–Eosin. Based on the results, the sex ratio was 1M:1.16F. The age groups for males and females were 0-4 years. The maximum length (TL) and weight of males were 16.02 cm and 53.7 g, and those of females were 16.24 cm and 60.1 g. The average condition factor was 1.23 and 1.21 for males and females, respectively. The minimum and maximum absolute fecundity were 1250 and 21857 (9611±6539). The mean of the gonadosomatic index (GSI) was 1.46±1.36 in males and 1.60±1.18 in females. The GSI showed significant differences in different months in males, but there was no significant difference in females. The maximum value of GSI was observed in July for females and in March for males. According to histological studies, five stages of sexual maturity were observed, including immature, maturing, ripening, ripe, and spent. Based on GSI values, egg diameter, and histological studies, this species has a relatively long spawning period from late March to early July. Our results indicated that the ovary in C. macrostomum is group Asynchronous.   Histology, Egg diameter, Fecundity, GSI, Tigris 89 103 http://injbir.com/browse.php?a_code=A-10-1-30&slc_lang=fa&sid=1 Z. Ghafouri No Department of Fisheries, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, University of Tehran, Tehran, Iran S. Eagderi Yes Department of Fisheries, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, University of Tehran, Tehran, Iran H. Poorbagher No Department of Fisheries, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, University of Tehran, Tehran, Iran S.V. Hosseini No Department of Fisheries, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, University of Tehran, Tehran, Iran E. Çiçek No Department of Biology, Faculty of Art and Sciences, Nevşehir Haci Bektaş Veli University, 50300, Nevşehir, Türkiye