Studying diet of Iranian goby (Ponticola iranicus) in the rivers of Anzali Wetland basin

Iranian goby is an endemic fish that was described in 2015 from rivers of the Guilan province. This fish exists upstream and mid-stream of rivers and it is observed lowly in downstream and rarely in estuaries of rivers. This study has been done in 4 important rivers of Anzali Wetland (Chafrud, Khalkaee, Siahdarvishan and Pasikhan) and the main purposes were determination of diet spectrum and food preference of the fish and samples was caught using electro-shocker from spring 2016 until winter 2017. Results on 54 individuals with a total length 47-137mm showed that coefficient of vacuity, averages of relative gut length and feeding intensity, 8.5%, 0.51±0.10 and 337.3±237.6, respectively. The studied fish fed on 26 food items belong to 21 animal families of worms (Oligochaeta), Bivalvia, insects consist of orders Coleoptera, Diptera, Ephemeroptera, Trichoptera, Crustacean (Isopoda and Palaemonidae) and bony fishes (Cyprinidae, Cobitidae and Gobiidae). Chironomidae, Baetidae and Simulidae were observed in 48.1, 14.8 and 11.1% of studied stomachs and they comprised about 74.3, 7.6 and 3.2% of total counted preys and were abundant. In general, the fish is a euryphagous and mainly benthivore fish and old individuals consume on nekton such as shrimps and fish species, too.