Feeding habits of sand goby Neogobius pallasi (Berg, 1916) in The Kaboodval, Zaringol and Shirabad Streams- Golestan Province

The purpose of this study was to determine the diet spectrum, feeding preference and feeding rate of sand goby. The present study was carried out in the Kaboodval, Zaringol and Shirabad Streams in summer 2008. In this regard, 104, 30 and 62 fish individuals were analyzed in the mentioned streams, respectively, and their diet regime were investigated. Based on the vacuity index, the sand goby presented in the Kaboodval, Zaringol and Shirabad Streams was classified in relatively gluttonous, relatively low fed and gluttonous groups, respectively. In this study, the food spectrum of the sand goby was broad and the fish was fed with the larvae of insects, crustaceans, Oligochaeta, gastropods and goby fish. Furthermore, the determination of digestive tract contains showed that the sand goby was fed with thirteen different kinds of food preys, in that Diptera (mainly Chironomid larvae) and Ephemeroptera in the Kaboodval and Shirabad Streams, the Ephemeroptera, Trichoptera and Diptera (mainly Chironomid larvae) in the Zaringol Stream were a most common food preys. According to the values of the Ivlev's selectivity index, the Ephemeroptera showed positive values in all three Streams and Diptera had negative values. According to Fp index, Diptera was also considered as the main food prey in the Kaboodval and Shirabad Streams while it was secondary food prey in the Zaringol Stream. Based on the results of this study, it can be concluded that the sand goby displays a generalistic and highly flexible feeding strategy due to its ability to use locally available food resources.