Juveniles of H.reidi were lightly anaesthetized at MS-222 concentrtion of 50 mg L (Olivotto et al., 2008 ).Wilson et al.(2006) iused benzocaine at 10 mg L for recording weight in H.abdominalis juveniles, whereas adults of H.reidi were anaesthetized in a benzocaine solution (50 mg L) befor sacrificing them for histological analysis by Martins et al. (2010). Castro et al.(2008) anaesthetised adult H.reidi with clove oil (0.05%) for assessment of diet composition.