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Aims: Being important both economically and in terms of protection, Luciobarbus capito is at risk of extinction. There are very few studies about the fish of Shahid Rajaee dam and the Tajan River. A significant number of Luciobarbus capitos is present in the dam and upstream. The present study was conducted with the aim of evaluating the growth characteristics and nutritional strategies of Luciobarbus capito in reservoir behind the Shahid Rajaee dam, Sari.
Materials & Methods: The present experimental study was carried out on 180 Luciobarbus capitos in Shahid Rajaee dam, Sari during 4 seasons of 2014 to 2015. The samples were fixed in formalin 10% and the biological and nutritional factors related to growth were investigated. The data were analyzed with SYSTAT 9 and Excel 2003 software.
Findings: The sex ratio of males to females was 1.14/1. The growth pattern of this allometric species was negative (w=0.015×L2.888; b=2.888). In males, allometric was positive and in females, allometric was negative. The mean length and weight of male and female had a significant difference (p<0.05), and the relationship between length and weight in fish was progressive. This species approaches the maximum predicted length with a growth rate of 0.1; the maximum estimated length for fish was 138.6 cm. Nutritional behavior index for under 4 years group showed a herbal diet (RLG=2.4±0.1) and, after puberty, it was inclining to a whole foods diet (RLG=1.2±0.6).
Conclusion: The allometric growth pattern is a negative for Luciobarbus capito, and in all seasons, it has a whole foods diet. 
 

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Aims This study was conducted to determine the Exotic fish food strategy of rainbow trout escaped from cultivating cages located in the southern basin of the Caspian sea (Mazandaran).
Materials & Methods A total of 90 specimens of this species were collected during the period from September 2017 to may 2018 from bony fish from west to central coast of Mazandaran. Sample of fish were biomediated and the age was determined by scales and operclum.
Findings The relative frequency of food items were Balanus glandula , Clupeonella cultriventris , Cerastoderma lamarcki, Neogobius fluviatilis،  Atherina caspia ،Chelon saliens ، Chinavia hilaris  ، Taxiphyllum barbieri ، Rutilus kutum، Cumacea،  Syngnathus  caspius  and  Gasterosreus aculeatus respectively. The result showed that a wide range of food was more central than the west, the fullness index in the female was more than male and in age groups older than 2 ⁺ and 3 ⁺ is more than 1 ⁺ (P>0.05). The fullness index, especially in the spring, increased significantly, the presence of B.glandula  more than C. cultriventris, but its relative importance was less than C. cultriventris (P> 0.05). 
Conclusion This fish has a carnivorous behavior and uses a wide range of foods, so it is possible to compete with many species of Caspian sea fish such as Salmo caspius. The effects of the adaptations and behavioral, physiological and ecological mechanisms of C. cultriventri and B.glandula  were more important in fish feeding.