The present study aims to give some details about the normal anatomical and histological structure of the liver, pancreas and gall bladder in Cyprinus carpio Linnaeus, 1758 and Mesopotamichthys sharpeyi (Günther, 1874). Anatomical results revealed that the liver of C. carpio is a reddish-brown in color, located in the anterior part of abdominal cavity and dispersed between most of the intestines, which is divided into two lobes; while in M. sharpeyi the liver is light brown in color located in the anterior part of abdominal cavity and extends to the end of the intestinal tract with two lobs. The gallbladder situated in the right side of the liver in both species. Histological results in both species showed that the liver consists

The present study attempts to identify some of the differences between the skull bones of two species Cyprinus carpio and Carassius carassius, which belong to the Cyprinidae family. The study is a taxonomic diagnostic study between the two species which are considered local fish abundant in the Iraqi aquatic environment

 The present study aimed to estimate percentage of red and white muscles fibers in two species of bony fishes belong to two different families which represented by Tenualosa ilisha (Hamilton , 1822) that belongs to the family Clupeidae and Cyprinus carpio (Linnaeus , 1758) that belongs to the family Cyprinidae . The samples were collected from local market at holy Karbala province. The results show difference clear in mean values of muscles numbers at different studied length groups, and the percentage of red muscles fibers were less than that of white muscle fibers at different body regions (R1,R2,and R3) among species.  The total average of red muscle fibers values ranged between (4.23 - 11.08 %) while the total average of wh

Hematological parameters were used as a biomarker of sub chronic effect of dursban  in Cyprinus carpio L. The common carp was exposed sub chronically to the 36, 53,113 µg /l concentrations of dursban for six weeks. During the experimental period the results showed a decrease  in the  red blood cell (RBC), white blood cell (WBC),  hemoglobin (Hb), mean corpuscular volume (MCV),  and packed cell volume (PCV)  in the  last two weeks of exposure, while the Mean corpuscular hemoglobin (MCH) and Mean corpuscular hemoglobin concentration (MCHC) were significantly increased. The present study indicates that sub chronic exposures of C.carpio to dursban alter the hematological parameters.

    The monogeneans Gyrodactylus dzhalilovi Ergens & Ashurova, 1984, G. magnus Konovalov, 1967 and G. matovi Ergens & Kakachava-Avramova, 1966 were recorded in this study for the first time in Iraq from gills of the common carp Cyprinus carpio Linnaeus, 1758 collected from Tigris River in Baghdad city. The description, measurements and illustrations of these parasites were given.

The acute toxicity effects of (2,4-D) pesticide to the common carp and grass carp was determined through 24, 48, 72 and 96 hr. Group of eight Common carp (Cyprinus carpio L., 1758; Pisces, Cyprinidae) and group of eight of grass carp (Ctenopharyngodon idella) were exposed to the 2,4-d. Lethal concentration (LC50) was determined with probit analysis. The median lethal concentration (LC50) values for common and grass carp were (157.77, 157.25, 156.41 and 152.62) and (115.92, 114.92, 112.94 and 96.52) respectively. Behavioral changes of the above mentioned species were examined for various herbicide concentrations.

In present study, an attempt has been made to investigate the effect of Chlorpyrifos insecticide on carp Cyprinus carpio L. through acute toxicity bioassay. The LC50 were estimated as 1897, 1266, 985 and 792 μg/L during 24 , 48, 72 and 96 hr. respectively by using the concentrations 500 , 1000, 1500 , 2000, 2500 and 3000 μg/L indicating high sensitivity of fish to chlorpyrifos. The behavioral response observed in the fish were erratic swimming, loss of reflex, hyperactivities, decrease in appetite secretion of mucus, increase movement of operculum and hyperventilation . These effects increased with increasing concentration of the chlorpyrifos and duration of exposure.