Nwanna (2003) indicated that the best profit margin would be realized by replacing fish meal with 30% fermented shrimp head meal (FSHM) in the diet of C. gariepinus. In addition, Plascencia-Jatomea et al. (2002) concluded that shrimp protein silage could be included in tilapia diets at concentrations as high as 15%, improving fish growth rate. They demonstrated that 6% of shrimp protein hydrolysate (SPH) can be included in diets for Nile tilapia without reducing growth performance. In the present study total replacement of SBM by SSM depressed growth performance of the tilapia. This discre-pancy may be attributable to the method for processing the shrimp waste meal other than nutritional. Moreover, these results may be attributed to the high ash content of the diet, the high levels of chitin found in SSM. The exoskeleton of the shrimp is composed mainly of chitin, an N-acetylated glucosamine polysaccharide that forms part of the protein complex, and is considered to have low digestibility when fed to animals (Austin et al., 1981). Due to this low digestibility, chitin physically blocks the access of digestive enzymes to lipids and proteins, thus affecting the utilization of these nutrients (Castro et al., 1989; Karasov, 1990).