Food regim of wild Common carp (Cyprinus carpio) in Golestan Provise, Gomishan coastal area (Caspian Sea)

This research was conducted based on fishing season (autumn and winter) from October 2009 till March 2010 on 180 Wild Common carps (Cyprinus carpio) captured in the coast of Gomishan area in Golestan province,locate sout-east of Caspian Sea.Specimens were collected during 6 months (at least 6 times per month). All specimens were collected from beach seines in the field. Biometric parameters such as total length and weight were measured from all 180 collected specimens and registered in biometric forms. The autopsy was done and the guts were placed in 4 % formalin and transported to Biology Lab of Marine Science and Technology Faculty, North Tehran Branch Islamic Azad University. The the content of gut was emptied and examined. The gut relative length factor (RLG), gut vacuity Index (VI), gut fullness Index (GSI), frequency index (FP) of consumed food items & condition of factor (K) were determind. Statistical analysis was done using T-test and oneway ANOVA. Graphs were made software. The average of relative length of gut of all age groups (2+-10 years) was 1.67 ±0.11 cm; the results of statical tests were not significantly differents during various seasons (P> 0.05). The average of gut fullness index was 22.63 ±9.99; the results were significantly different during various seasons (P< 0.05). The (VI) was calculated 71.11%, which shows these species are abstemious. Gut content included Ploychaeta, Oligochaeta, Bivalvia, Gastropoda, Ostracoda, Foraminifera, Gobiidae fish remains, Invertebrate eggs, Crab and Parts of plants. Greatest value of (FP) among all age groups belonged to Polychaeta (63.89%).Values of the index showed no significant different in the period (P>0.05). Polychaeta(63.89%) were the main food (FI>50%); Bivalvia(35.00%) , Parts of plants(34.11%) ,Balanus(16.11%) , Crab(32.22%) , Fish remains(44.22%), Oligochaeta(11.67%) , Invertebrate eggs(42.78%) , Gastropoda(36.67%) , Trematod(25.54%) and Ostracoda(12.78%)  were occasional food (10%<FI<50%) , Cumacea(6.67) , Amphipoda(2.78), , Foraminifera(3.33) were random food (FI<10%). The average of index of (K) was 1.39 during the period which shows good nutrition in Wild Common carp.