Abstract: The morphological and structural characteristics and karyotypes were observed in forty-seven samples of American shad Alosa sapidissim by anatomy.The fish has a moderately fusiform body,and is silvery in color with blue or blue-green metallic luster on back.The fish has point mouth with lower jaws,well developed eyelids,large cycloid scales,and lateral line poorly developed with 56-62 scales.Gill rakers are long and slender with 24-31+ 47-55 gill rakes on the first arch.The soft fin rays are found to be as:D,3―13-16;V,1―8;P,1―16-17;A,1-2―17-19;C,distinctly forked,23.The measurable morphological parameters of the fish are also described.The Y-shaped stomach is well developed with slender pyloric caeca of 92-115.The swim bladder consists of one anterior chamber and one posterior chamber.The relationship between body length(L)and body weight (W)was expressed as W=0.0096L3.1429(n=47,R2=0.9753)and the condition factor was 1.53.The diploid fish has chromosome number of 2n=48 and the karyotype is found 4sm+44t,NF=52,and no strange size chromosomes related to the sex was observed.
2011, Vol. 26 
