دراسة مقارنة بين نسب وأقطار الألياف العضلية الحمر والبيض في سمكتي الكطان Luciobarbus xanthopterus (Heckel,1843) والشلك Leuciscus vorax (Heckel,1843) في نهر الهندية , محافظة كربلاء.

A comparative study between the ratios and diameters of the red and White muscle fibers in the fishes of Luciobarbus xanthopterus (Heckel,1843) and Leuciscus vorax (Heckel,1843) In Al-HIndia River, Karbala governorate

the current study included Some aspects of life for two types of freshwater fish as a comparative study, by knowing its activity swimming , represented by calculating some histological characteristics of red and white skeletal muscles by calculating the proportions and diameters of muscle fibers of both types red and white , in two different regions of the body (R1,R2) of two types of bony river fish (Teleost) , in the Shatt al-Hindi waters (Euphrates River) in the holy Karbala Governorate For the same fresh aquatic environment with different food and they are namely : Luciobarbus xanthopterus (Heckel,1843) from the Cyprinidae and Leuciscus vorax (Heckel,1843) from the Leuciscidae , which belong to, where the study continuted from the beginning of September (2021) to the end of December (2021) , using gill nets with different openings , and (50) fish of both types were collected and divided into five groups of different length in their groups , their lengths ranged between (300-440) mm and their weights ranged between (300 – 1000) g for both groups .
The results of the current study showed that the proportions of red muscle increase as the length of the fish increase in both species this indicates the existence of a strong direct relationship between the average ratio of red muscle ratios and the average length of fish , and this was explained by the values of the correlation coefficient that were (0.98 and 0.99) in the L. xanthopterus and L. vorax respectively, it was noted that the rates of red muscle ratios in the posterior region (R2) were greater than the frontal region (R1) , and this means that the rate of red muscle ratios differed according to the studied body regions in both types , the values of their averages in L. xanthopterus ranged between (12.22 – 18.32) % , while their average values were (13.37 – 17.65) % in L. vorax , and it was noted that the percentage of white muscle decreases as the length of the fish increases .
This indicates that there is a strong inverse relationship between the average percentage of white muscle and the average length of fish ,and this was shown by the values of the correlation coefficient that were (- 0.97 and – 0.96) in the L. xanthopterus and L. vorax respectively , and the rates of white muscle ratios in the anterior region (R1) were greater than the posterior region (R2) , and this means that the rates of white muscle ratios different according to the regions of the body studied in both types , the values of their rates in the L. xanthopterus between (86.67 -80.96 )% while the values of their rates (86.29 – 82.39) % in the L. vorax , so the fish of the current study were considered among the group of Sprinters fishes because they contain a high percentage of white muscles , the results of the current study proved that the total ratio of the red muscle ratios (15.5 and 15.3) % in the L. xanthopterus and L. vorax respectively , therefore the fishes of the current study are considered among the two types of fish of medium kinetic activity ( intermediate swimming).
The results of the phenotypic histological examination of the structure of the muscle tissue in the current study demonstrated that the diameters of the red muscle fibers were of small sizes and almost identical in shape in the areas of the body studied (R1 ,R2) ,while the diameters of the white muscle fibers were large and varied and irregular in mosaic shape in both types studied , the average values of its diameters ranged in L. xanthopterus between (42.45 – 46.38) micron ,while the average of its diameters were (31.24 – 46.41) micron in L. vorax , it was noted that the rates of the diameters of the red muscle fibers increased with the increase in the length of the fish ,and this was explained by the value of the correlation coefficient that was (0.97 and 0.98) in the L. xanthopterus and L. vorax respectively , this indicates that there is a strong direct relationship between the average diameters of the red muscle fibers and the average length of fish , and that the average diameters of the red muscle fibers in the anterior region (R1) were greater than the posterior region (R2) this means that the rates of the diameters of the red muscle fibers differ according to the areas of the body studied in both types , the diameters of the white muscle fibers showed a clear difference in their average values , as the average values of their diameters in the L. xanthopterus (69.77 – 73.87) micron , while their average values were (57.25 – 69.32) micron in the L.vorax , as the rates of the diameters of the white muscle fibers increase with the increase in the length of the fish ,and this was shown by the values of the correlation coefficient that were (0.98 and 0.99) in the L. xanthopterus and L. vorax respectively , The indicates that there is a strong direct relationship between the average diameters of white muscle fibers and the average length of fish , And that the average white muscle fiber diameters in the anterior region (R1) were greater than the posterior region (R2) , This means that the rates of the diameters of the white muscle fibers differ according to the regions of body studied in both types , Meaning that the values of the rates of the diameters of the red and white muscle fibers decrease towards the back (caudal peduncle) for its importance associated with the swimming of both types of fish.