The queen conch Strombus gigas is a marine resource of ecological and economical importance in all the Caribbean countries. A severe depletion of most populations due to over-fishing is forcing the establishment of regulatory measures and closure of fishing areas in most Caribbean countries. Aquaculture programs are developing in the USA, Turk and Caicos, as well as Mexico and some other countries. However, one of the bottlenecks for queen conch culture is the lack of well adapted formulated food for optimal growth in high density rearing. Nutrient requirements for conch juveniles are slightly well-known (Davis 2000 and Aldana Aranda, et al. 2007). To assess the natural diet of queen conch the examination of stomach contents was made from individuals fed with natural foods in the field. The stomachs of conchs fed with natural foods were studied by analyzing stomach contain by optical microscopic with taxonomic references of Joly (1967), Jahn, et al. (1979), Brusca and Brusca (1999) and Graham and Wilcox (2000). The total number of items in stomach contents was 22, which 15 were in adult and 12 in juveniles. The most diverse Phylum was Rhodophyta with 5categories. The second largest groups were Cianophyta and Protozoa with three categories in each one. A seagrass had an important biomass in one of the adults. These data to help to adjust better the feed formulation and the frequency of feeding to the real need of organism according to their age and size.