3.4. Heavy metal content
The Cu, Zn, Pb and Cr contents of both species in the fish farm were all higher than those in the control site, with the exception of Cd (Table 4). While S. henslowianum grown in both experimental sites were higher than those of S. hemiphyllum, except Cu in the control site (Table 4). The heavy metal contents of S. hemiphyllum grown in both sites were all below the MAC. However, for S. henslowianum, heavy metal contents (Cd and Cr contents in the control site; Pb and Cr contents in the fish farm) were exceeded the MAC of aquatic feed