Metaschistura cristata is a small nemacheilid loach species found only in Turkeminstan and Iran. The present study reports data on its reproductive biology, based on 1029 specimens collected in the northeast of Iran. Specimens were collected at 12-month intervals from January 2009 to December 2010. Maximum age, based on opercula readings, was 6+ years for both sexes. Specimens ranged in size from 24 to 98 mm total length and weighted from 0.08 to 7.32 g. Length-weight relationships implied positive allometric growth for both sexes and sex ratio was 1:1. The gonadosomatic indicated that peak reproduction occurred during April and June, with highest average values of 2.11 ± 0.88 for males and 25.25 ± 0.52 for females in May. Oocyte diameter ranged from 0.09 to 1.58 mm; with a mean value of 0.54 ± 0.42 mm. Overall, the present study provides evidence that the population of Metaschistura cristata in the northeast of Iran is in the unique condition; however, more experimentation is necessary to determine biological preferences of this species.

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