Ca 1950 - 1970 ¬ Los Castillo mark is a Onix Negro marking which means sterling inlayed with a layer of black stone. Taxco Mexico. This fish is a wonderful example of the unusual pieces done in this time period by Castillo. Condition is fabulous and I will polish and clean it up upon request. The fish has sterling on both sides with a layer of onyx stone as his center. His eyes gill and tail have detailing in copper. A very interesting and collectible piece. Please use the zoom feature to really get a good look at the markings. Measures just under 2" and will arrive gift boxed.