The Collaborative International Dictionary of English v.0.48:

Candlefish \Can"dle*fish`\, n. (Zool.)
   (a) A marine fish (Thaleichthys Pacificus), allied to the
       smelt, found on the north Pacific coast; -- called also
       eulachon. It is so oily that, when dried, it may be
       used as a candle, by drawing a wick through it.
   (b) The beshow.
       [1913 Webster]