The Collaborative International Dictionary of English v.0.48:

Ablet \Ab"let\, Ablen \Ab"len\[F. ablet, ablette, a dim. fr. LL.
   abula, for albula, dim. of albus white. Cf. Abele.] (Zool.)
   A small fresh-water fish (Leuciscus alburnus); the bleak.
   [1913 Webster]