E. Mahdipour - Department of Marine Biology, Faculty of Marine Sciences, Tarbiat Modares University, Nur, Iran.
M.S. Alavi-Yeganeh - Department of Marine Biology, Faculty of Marine Sciences, Tarbiat Modares University, Nur, Iran.
I. Sharifpour - Iranian fisheries research institute, Tehran, Iran.
H. Ahnelt - Department of Theoretical Biology, University of Vienna, Vienna, Austria & First Zoological Department, Natural History Museum in Vienna, Vienna, Austria

This study provides fundamental information on some key aspects of the reproductive biology of Neogobius caspius, a Caspian Sea endemic, poorly studied Gobiidae fish species. In total, ۲۲۲ specimens were captured monthly from Noor coastal waters in southern part of the Caspian Sea from April to October ۲۰۱۶, while water parameters (temperature, salinity and pH) were monitored weekly. Gonadosomatic and hepatosomatic indices suggested that the reproductive period of this species was in April to May. Peak of Fulton and Clark’s condition factors appeared in April and May for female and male specimens, respectively, then a declining trend appeared until June that remained constant until the end of October. Absolute fecundity ranged from ۴۱۸ to ۱۷۹۸ oocytes per individual (mean: ۱۰۱۳±۳۵۷ (SD) oocytes, n=۴۱), which was highly related to the length and weight of fish and weight of gonads. Oocyte mean diameter ranged ۳۵.۸۵±۱۱.۸۰ µm in immature stage to ۱۱۰۳.۸۶±۱۷۲.۰۱ µm in mature stage. Five stages of maturity for female and four stages for male specimens were described based on macroscopic features and histological description. N. caspius appeared as an iteroparous and a batch spawner species, producing more than one oocyte clutch in a single reproductive season.

Gobiidae, Gonadosomatic Index, Hepatosomatic Index, Caspian Sea