An increase of weight gain has been reported in channel catfish fed phytase supplemented diets containing only plant
protein or a combination of plant and animal protein sources (Jackson et al., 1996). The supplemental effect of phytase on growth performance in fish cannot be directly compared because it may differ depending on fish species and rearing conditions, and more specifically on dietary composition in each feeding study (Cao et al., 2007). Generally, growth
improvements have been observed in studies that used plant-based diets supplemented with phytase; however, results have been somewhat inconsistent (Cao et al., 2007). Oddly, assuming that increased phosphorus availability would lead to increased bone formation, no significant differences were seen in ash content of C. striata with phytase
supplementation, although ash content of C. micropeltes did decrease significantly with greater levels of SBM inclusion when all SBM diets had phytase supplementation.