Reproductive biology of Cobitis keyvani (Cobitidae) from the Talar River in the southern Caspian Sea basin



 Some aspects of the reproductive
biology of Cobitis keyvani (Mousavi-Sabet, Yerli, Vatandoust, Ozeren and
Moradkhani, 2012), an endemic Loach fish species from the Talar
River in the southern Caspian Sea basin, in north of Iran was studied by
regular monthly collections throughout a year. Fecundity, condition factor, gonado-somatic, modified gonado-somatic
and Dobriyal indices were estimated. Regression analyses tested the
dependence of fecundity on fish length, weight, gonad weight and age. Significant differences were observed between the
total number of females and males, females being more abundant. The mature
females and males were longer than 49 and 45 mm in total length, and +2 and +1
in age, respectively. The average egg’s diameter was 0.56 mm. The
spawning of Cobitis keyvani from Talar River took place from May to late
July, when the water temperature is between 18.7 to 24.0°C. At the beginning of
the reproduction period, the average
GSI values were 10.09%, ranging from 6 to 25% in ripe mature females. The absolute and relative fecundity were 2211 and 586
respectively. The absolute fecundity was
significantly related to body weight and gonads weight. Based on the gonado-somatic and Dobriyal indices,
it was concluded that the fish has a prolonged active reproductive period.
Their long reproductive activity and high range of fecundity are types of
adaptation by short-lived small fishes to environmental conditions.