Most Asian country have been success for the culturing of the mud crab i.e. Thailand, Vietnam and Philippines but no action were taken to solve the barnacle infestation problem of mud crab. Previous study did not mention about significant of the attachment of pedunculate barnacle to the mud crab. But somehow, this pedunculate barnacle may be able to give effect to the mud crab respiratory system especially for adult mud crab. This preliminary study are to observe the effect of the pedunculate barnacle attachment to their host using histopathological and Scanning Electron Microscopy (Tabletop SEM 1000, Hitachi) observation. Histological sectioning of gill wild mud crab with the Hematoxylene and Eosin staining (H&E Stain) were done to study about their effect. The results show the attachment of the pedunculate barnacle is temporary and will be left the host-gill during molting period.