Reproductive behaviors and biological characteristics of the broods and larvae of the endemic fish Aphanius vladykovi Coad, 1988 (Cyprinodontidae) in Choghakhor lagoon of Chaharmahal-o-Bakhtiary, Iran

We studied the spawning sites of the endemic endangered fish Aphanius vladykovi in the littoral zone of the only remaining lake habitat, Choghakhor lagoon. During this study, we inferred by the direct observations of the spawning and the location of spawned eggs, the reproduction behaviors of the broods which was used to determine their preferred spawning nests. It revealed that the nest abundances of the species clearly related to the spawning substrates, such as gravel bottom and the special aquatic vegetation as well as the depth and the distance from the shore. Due to the water level depletion, the initial habitat of the fish (depth 55±1.1 and 555±18.8 cm from the shore) has been modified and degraded and often there is an apparent lack of suitable spawning substrates (lower depth 40±1.2 and less distance 190±12.2 cm from the shore). Growth models for both sexes were stated by the von Bertalanffy function as Lt=4.25(1-e-0.37(t-0.89)) for females and Lt=4.12(1-e-0.37(t-0.83)) for males. The weight-length relationship was described as W=0.026 L3.01 (r2=0.97) for males and W=0.026 L3.03 (r2=0.98) for females. The slope of the regression line (b) fitted through the weight-length data suggesting a positive allometric growth model for both the females and the males. It is concluded that the habitat specialization of the limited zone of spawning is an important element in the survival of the endangered fish as a critical stage in the habitat requirements of its population.