Effect of Food Availability on Some Biochemical Responses in the Target Organs of Mugil cephalus Inhabiting Abu-Qir Bay, Alexandria, Egypt

Document Type : Original Article


Department of Zoology, Faculty of Science, Al-Azhar University


The present study aimed to determine food and feeding habits of Mugil cephalus collected from Abu-Qir Bay, Egyptduring the period from July, 2017 to June, 2018 and its effect on the nutritional values (total proteins, total lipids, total carbohydrates) in the target organs (kidney, liver, and muscles) of the commercial fishes, M. cephalus.
Results indicated that, the rate of feeding activity of M. cephalus was peaked during summer and declined during winter. The maximum value of feeding activity was recorded in the larger fish during summer and autumn and the minimum values occurred in the smaller one during autumn and winter. In the present study, the changes in feeding activity appear to be correlated with water temperature and the availability of food in nature.
           The biochemical composition of fish organs is a good indicator of the fish quality and physiological condition. Data declared that the minimum value of total proteins in the kidney and liver was observed in the small size during the summer. Moreover, the percentages of protein contents in the muscles of M. cephalus are usually affected by several factors including the type of food, fish size and seasons. It was declined during autumn in the small fish.Results revealed that the maximum average values of total lipids in the kidney and liver of M. cephalus wererecorded in the large fishes during spring. Whereas, the minimum values were detected in the same size during summer. However, total lipids in the muscles attained its lower value in the small fish during summer and the higher ones in the large size during spring.The present study exhibited the increasing level of total carbohydrates in the kidney of M. cephalus, during spring in large size of fishes and the decreasing value occurred in the same group during autumn. On the other hand, total carbohydrates in the liver showed seasonal variations with an increasing level in the large fishes during autumn and the decreasing level occurred in the same group during spring. However, total carbohydrates were peaked in the muscles of the small-sized group during autumn and spring and declined in the large one during spring.Although, the availability of food items during any season due to the optimum condition; it may reflect the lower level of nutritional values attributed to the changes in water quality by the action of pollutants, that may critically influence the growth rate and quality of the fishes which feed on flora and plankton induced by bioaccumulation of metals.Statistical analysis of metabolic parameters in the target organs at different sized groups of M. cephalus showed significant differences (p < 0.05) at one way of ANOVA between the different organs and between different parameters. On the other hand, it was non-significant differences in the interaction between organs and sized group, by using two ways of ANOVA.Such investigation may lead to a better understanding of some biological aspects like food chains, growth rates, productivity, mortality, and nutritional values as well as their trophic levels.