This topic got somewhat overshadowed by a topic on the general issue of common and rare words, partly inspired by the scrod issue.
To respond to the specific question, I agree that the word is uncommon outside the US. In the British National Corpus, it gets one hit, whereas the Corpus of Contemporary American English yields 35 hits. And from what RM and anonsi say, it seems to be regional within the US.
(I think I knew the word, as designating a fish of some kind, probably from Nero Wolf novels.)
I will derank this word to rare.