The Collaborative International Dictionary of English v.0.48:

Brit \Brit\, Britt \Britt\, n. (Zool.)
      (a) The young of the common herring; also, a small species
          of herring; the sprat.
      (b) The minute marine animals (chiefly Entomostraca) upon
          which the right whales feed.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

britt \britt\ n.
   1. the young of a herring or sprat or similar fish.

   Syn: brit.
        [WordNet 1.5]

   2. minute crustaceans, forming food for right whales.

   Syn: brit.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

britt
    n 1: the young of a herring or sprat or similar fish [syn:
         brit, britt]
    2: minute crustaceans forming food for right whales [syn:
       brit, britt]