دراسة تشريحية مقارنة في المساحة التنفسية وأقطار الألياف العضلية الحمر والبيض بين نوعين من الأسماك العظمية في شط الهندية ,كربلاء

A comparative anatomical study of the respiratory area and the diameters of the red and white muscle fibers between two types of bony fish in Shatt al-Hindi, Karbala

The current study included the of two species of freshwater Teleosts, the Luciobarbus xanthopterus (Hecel, 1834), which belongs to the family Cyprinidae, and the Coptodon zillii (Gervais, 1848), which belongs to the Cichlidae family from the Shatt al-Hindi (Euphrates). The study continued from the beginning of September 2019 to the end of December 2019, and (50) fish were used for every studied species, distributed into five different length groups, where their length averages ranged between (100-300mm) and their weight averages ranged between (26-620 gm), as the current study deals with a comparative study of some aspects related to the locomotor activity of fish , which include analysis of the Gill Respiratory Surface Area and some histological features of the skeletal muscles (Red and White) through the account of the diameters of these muscle fibers in two different body regions (R1,R2) for each type of species studied. The results of the measurements of the Gill Respiratory Surface Area showed when studying the correlation coefficient between the length of the fish and the three components of the Gill Respiratory surface areas of (mm²), which are :the average of the total length of the Gill filaments, number of secondary lamellae per mm, and the area of bilateral secondary lamellae, there was a direct correlation between fish length and total length of the Gill filaments values, as correlation coefficient values reached (0.95 – 0.98) in L. xanthopterus and C. zillii, respectively, while the correlation was inversely between fish length and the number of secondary lamellae, The values of the correlation coefficient reached (0.99 – 0.95) in the L. xanthopterus and C. zillii respectively, while the correlation was direct between the fish length and the area of bilateral secondary lamellae, so the values of correlation coefficient reached (0.98 – 0.97) in L. xanthopterus and C. zillii respectively, and the differences recorded for the components of total gill surface area (mm2 ) when analyzed statistically showed the presence of significant differences (p <0.05) when studying the values of the three respiratory area components for both studied species. as the results of the current study showed the effect of fish length on the total (mm2 ) and relative gill respiratory surface area (mm2/gm), a strong direct correlation was observed when studying the relationship between fish length and the Total surface areas, The values of correlation coefficient reached (0.90 – 0.97) in L. xanthopterus and C. zillii respectively, but when studying the correlation relationship between length The fishes and relative gill respiratory surface area (mm2/gm), was inversely correlation between them, as the values of (r) reached (0.96-0.97 ) in the L. xanthopterus and C. zillii fish, respectively, and the differences recorded for total and relative gill respiratory surface area showed when statistically analyzed there were no significant differences (p ><0.05) for total (mm2) and relative gill respiratory surface area for both fishes studied. The L. xanthopterus and C. zillii were counted among the intermediate fishes, depending on the rates of the total length of the Gill filaments, Where it reached total length of the Gill filaments (2252.71 – 5623.12) mm in the L. xanthopterus and C. zillii, respectively. The current study showed that the rates of red muscle fiber diameters were always lower than the rates of white muscle fiber diameters in the current study fish, as the total rates of the red muscle fiber diameters ranged between (21.73 – 41.71 microns) in both studied types, while the total rates of white muscle fibers ranged between ( 43.56 – 71.35 microns) in both studied types, in addition to the fact that the red muscle fibers were of small (sizes and diameters) almost identical in shape in both studied types, while the white muscle fibers were of large( sizes and diameters) and their different irregular mosaic shapes . Summary C The results of measuring the diameters of the red and white muscle fibers when studying the correlation relationship showed a positive relationship between the length of the fish and the diameters of the two type of muscle fibers. The values of correlation coefficient for the red muscle fibers ranged (0.99- 0.98) in the L. xanthopterus and C. zillii, respectively. The values of correlation coefficient for white muscle fibers (0.98 – 0.97) in the L. xanthopterus and C. zillii, respectively, and the results of the statistical analysis of the differences recorded for the total rates of the diameters of the red muscle fibers in the two studied species showed that there were no significant differences (><0.05 P) for all comparisons between the two fish species, As a result of the convergence of the rates of the diameters of the red muscle fibers in L. xanthopterus and C. zillii, respectively. and also the results of the statistical analysis showed that there are significant differences (P>0.05) between the L. xanthopterus and C. zillii when analyzing the the recorded differences of the total rates of the diameters of the white muscle fibers statistically. The current study showed the difference in the rates of the diameters of the red and white muscle fibers in the studied body regions (R1, R2) for both species, Diameters rates have been muscle fibers the red and white in the front region (R1) is greater than the rates in the region rear body (R2) in both species studied, the results of the statistical analysis of the differences recorded between the values of the rates of the diameters of red and white muscle fibers the studied body regions (R1, R2) studied the existence of significant differences (P>0.05) of the red muscle fibers between the anterior region (R1) and the posterior region (R2) and in both species studied. While there were no significant differences (P>0.05) for white muscle fibers between the anterior region (R1) and the posterior region (R2) for both species., the results of the current study showed a decrease in the rates of muscle fiber diameters of both species in the posterior region of the body (caudal peduncle), this decrease results from the increasing of new muscle fibers have small diameters and sizes, which leads to an increase in the flexibility and ability of the posterior region to contracture and relax, which reflects the importance of the caudate peduncle in association with the tail fin in the mechanism of movement or swimming of the fish.