1.  whitebait(n = noun.food) - minnows or other small fresh- or saltwater fish (especially herring); usually cooked whole;
is a kind of herring

2.  whitebait(n = noun.animal) - the edible young of especially herrings and sprats and smelts;
is a kind of young fish
is a member of malacopterygian, soft-finned fish

   The young of several species of herrings, especially of the common herring, esteemed a great delicacy by epicures in England. [1913 Webster]

whitebait, n. (pl. same)
1 (usu. pl.) the small silvery-white young of herrings and sprats esp. as food.
2 NZ a young inanga.