Traditional methods of control using chemical treatments are not always effective. They can be costly, cause problems of pollution and of drug resistance in the pathogen, and they may be subjected to prohibitive legilisation. Newer techniques of immunizing fish are still in early stages of development. At present it is not possible to assess just how important these will become. They may prove to be more applicable to brood stock rather than on growing fish, and to intensive systems rather than the more traditional fish farming systems. In the present work, an effort was made to find out an antigen that can protect fry fish against infection with Ichthiophthirius multifiliis. Juvenile grass carp fish were immunized against I. multifiliis. Two vaccines were developed; heat attenuated vaccine and whole parasite crude antigen. The routes of immunization were; I.P. injection, skin scraping and bath immersion. The percentage of relative protection (PRP) was studied for immunized fish in contrast to non immunized ones. Comparison between PRP afforded by both vaccines were done. A modified method was developed to produce heat attenuated vaccine. The attenuated vaccine gave more protection than the crude one. Fish immunized by the living attenuated vaccine show PRP of 100%, 70% and 10%, for I. P. injection, skin scraping and bath immersion routes of vaccination respectively. While that for fish vaccinated with crude antigen were 50%, 30%, and 00% respectively.