Cryptotrema seftoni, the Hidden blenny, is a species of labrisomid blenny known only from Angel de la Guarda Island, in the Gulf of California This species is a deep water species known to occur on rocky reefs at depths greater than . No specimens of this fish have been collected since 1952 and it is poorly known. The specific name honours Joseph W. Sefton Jr. (1882âÂÂ1966), a banker from San Diego, California, from whose yacht the type was dredged.