From The Collaborative International Dictionary of English v.0.48 :
Lance fish \Lance" fish`\n. (Zool.)
A slender marine fish of the genus Ammodytes, especially
Ammodytes tobianus of the English coast; -- called also
sand lance.
[1913 Webster] Lancegay
From WordNet (r) 3.0 (2006) :
sand lance
n 1: very small silvery eellike schooling fishes that burrow
into sandy beaches [syn: sand lance, sand launce, sand
eel, launce]