Although　immersion　and　oral　vaccination　are　the　most　practical　methods　for　fish　farmers,　their　applications　are　very　limited　due　to　low　immune　stimulation　effect.　We　used　the　protein　transduction　domain　(PTD)　of　transactivating　transcriptional　factor　(TAT)　derived　from　HIV　TAT　protein　to　increase　the　delivery　efficiency　of　aquatic　protein　vaccines.　Vibrio　parahaemolyticus　outer　membrane　protein　K　(ompK),　a　reported　vaccine　candidate　for　the　prevention　of　V.parahaemolyticus　infection,　was　fused　with　TAT-PTD　expressed　in　Escherichia　coli.　We　found　that　PTD-ompK　fusion　protein　effectively　penetrated　into　marbled　eel　bodies.　Analysis　of　ompK　antibody　titres　demonstrated　that　immersion　vaccination　with　PTD-ompK　was　superior　to　ompK　alone　and　induced　robust　immune　stimulation　in　marbled　eels.　Both　active　and　passive　protection　analyses　against　immersive　challenge　with　V.parahaemolyticus　strains　demonstrated　that　marbled　eels　immunized　with　PTD-ompK　survived　significantly　longer　than　those　immunized　with　ompK　alone.　Our　results　indicated　that　TAT-PTD　could　be　served　as　is　an　efficient　delivery　system　for　aquatic　immersion　vaccinations　against　various　infectious　diseases　commonly　seen　in　aquatic　farm　industry.