The invention discloses a novel wide spectrum aquaculture pharmaceutical, comprising a therapeutic, disinfective and/or anesthetize effective amount of a preparation comprising TTO in a stable water-in-oil emulsion of alkali or ammonium salts of organic fatty acid; said emulsion is also stable when converted into an oil-in-water emulsion, wherein the preparation is for the treatment of aquatic animals suffering from a disease selected from bacterial, parasitic, viral and mycotic diseases. The invention also discloses a method for treating diseases selected from bacterial, parasitic, viral and mycotic origin, in an aquatic animal suffering therefrom, which method comprises administering a therapeutic active amount of a preparation comprising TTO in a stable water-in-oil emulsion of alkali or ammonium salts of organic fatty acid; said emulsion is also stable when converted into an oil-in-water emulsion to said aquatic animal.