Solid state fermentation has been advocated for its advantages over the submerged fermentation in select situations. The technology is of special application where microbial exoenzymes, the cells and their products are to be retained within the produce. This book describes importance of several locally isolated bacteria in improving nutritional status of fish feed, promoting the growth of cultured Rohu fingerlings. Moreover, the probiotics reported in this work qualify the status of controlling bacterial fish diseases. It is hoped that the probiotics will find increasing application in the promotion and development of aquaculture. While formulating fish feed a major cost incurring ingredient is protein source. The probiotics while fermenting low cost agriwastes increase protein content in the form of exoenzymes and single cell protein. This aspect is likely to bring new fish feed formulations.