The Caspian tadpole goby (Benthophilus macrocephalus) is a species of goby which is widespread in the basin of the Caspian Sea, specifically in the near-estuary zone of the rivers and in small bays. It is a common species in the Volga River delta near Astrakhan, occurred in the deltas of rivers Terek, Ural, Samur.[1] During the warmer months, this species prefers to live at depths of from 0.5mto10mm (01.6feetto30feetm), moving in the colder months to depths of 20mto25mm (70feetto82feetm). It can reach a length of 11.6cm (04.6inches) TL.