The Collaborative International Dictionary of English v.0.48:

Roach \Roach\, n. [OE. rroche; cf. AS. reohha, D. rog, roch, G.
   roche, LG. ruche, Dan. rokke ray, Sw. rocka, and E. ray a
   fish.]
   1. (Zool.)
      (a) A European fresh-water fish of the Carp family
          (Leuciscus rutilus). It is silver-white, with a
          greenish back.
      (b) An American chub (Semotilus bullaris); the fallfish.
      (c) The redfin, or shiner.
          [1913 Webster]

   2. (Naut.) A convex curve or arch cut in the edge of a sail
      to prevent chafing, or to secure a better fit.
      [1913 Webster]

   As sound as a roach [roach perhaps being a corruption of a
      F. roche a rock], perfectly sound.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fallfish \Fall"fish`\, n. (Zool.)
   A fresh-water fish of the United States (Semotilus
   bullaris); -- called also silver chub, and Shiner. The
   name is also applied to other allied species.
   [1913 Webster]