texturing a swordfish

Dear All,

I’m on a mission to create a realistic looking swordfish. Due to the end use of the model, there are a few limitations: the file size can’t get too big (I’m refraining from subdividing the mesh, sculpting, etc.) and there can only be one map attached, the texture map (so no bump map, normal map, etc.).

Please take a look at the attachments: two screen shots of the model and one reference picture (more references are found on Google Images searching for “swordfish” or “Xiphias gladius”)
Right now I have one texture map and two procedural textures – clouds and voronoi – influencing the normals.

Do you have any suggestions on how it can be improved?
Thank you, I really appreciate your opinion