The scanning electron microscope permits a high resolution microscopic examination of surfaces. In this study the scanning electron microscope has been used to visualize the microflora on the various surfaces of fish with special attention to the salmonid. The technique reveals that areas of the skin have a rich and varied bacterial population which appears to be associated with the mucous layer. The gills of healthy fishes are seen to be essentially free of bacteria. Very few bacteria are seen to be associated with the gastrointestinal mucosa. Most of the bacteria present on this mucosa appear to be associated with particles of food.  Electron micrographs of these various populations and surfaces will be shown and will include examples of some disease states.