Study of food habits of three Neogobius species in the Central south part of the Caspian Sea, Noshahr

Family Gobiiade which are massive consumers and serious competitors for other species, are recognized as one of the most abundant fishes in the Caspian Sea. This study conducted in the Noshahr coast, Central south part of the Caspian Sea from March 2012 to September 2013 in 14 sites. This study examined food habits of the three Neogobius species such as, Neogobius pallasi, Neogobius melanostomus and Neogobius caspius. Totally, 400 Caspian sand, 191 Round and 161 Caspian gobies were captured. overall 10 prey items were determined, Xanthidae, Palaemonidae, Bivalvia, Barnacle, Polychaeta, Gammaridae, Ostracoda, Foraminifera, fish remains and fish eggs. There was no main food item in the diet of Caspian sand and Round gobies in the study period and Caspian goby consumed Gammarus mainly. Bivalvia (%28.68) was more abundant prey item in the diet of Caspian sand goby. barnacle (%23.31), Ostracoda (%21.83) and polychaete (%20.03) were more abundant prey items in the diet of Round goby and Gammarus (%59.78), was more abundant food in the diet of Caspian goby. Vacuity index was high in spring, decreased at summer then increased at autumn. The feeding strategy of Caspian sand and Round gobies were more specialized. Fish predators were specialized on distinct prey items. Caspain goby had a mixed feeding strategy and Gammarus was recognized as an important food. Shannon index had a significant difference between Caspian sand (1.4±0.24) and Caspian gobies (0.78±0.35), Round goby (1.32±0.43) and Caspian goby too.