Two species of Red Sea puffer fishes L. sceleratus Fig. 1 and A. hypselogenion Fig. 2, were chosen for the present study. The crude bioactive materials from their ovaries and skin mucus were isolated and their antifouling property was tested. The samples were collected from the Red Sea fishing ports and were taken to the laboratory of NIOF (National Institute of Oceanography and Fisheries) in Suez for immediate processing. The ovaries of L. sceleratus were homogenized with 1% acetic acid. The obtained homogenate was centrifuged at 2700 rm. Then the pellet re-extracted twice with the same volume of 1% acetic acid solution. The supernatant was concentrated under reduced pressure and then defatted by shaking gently with an equal volume of dichloromethane three times. The aqueous layer was collected and concentrated under reduced pressure to remove residual dichloromethane. The resulting crude extracts were stored in a freezer till later testing.