The objective of this study was to evaluate the effects of fishmeal (FM) replacement with corn protein concentrate (CPC) on growth performance, nutrient utilization, gut morphology and skin coloration of red hybrid tilapia, Oreochromis sp. Five isonitrogenous (350 g/kg crude protein) and isolipidic (10 g/kg lipid) diets were formulated to contain CPC that substituted 0%, 25%, 50%, 75% or 100% FM. Diets were fed to triplicate groups of tilapia (mean initial weight, 10.33 ± 0.02 g) twice daily for 63 days. The results showed that replacing up to 50% FM in red hybrid tilapia diet with CPC did not show any significant adverse effects on growth, feed utilization, haematocrit counts, condition factor and gut morphology of tilapia (p > 0.05). However, replacing 75% or 100% FM with CPC had deleterious effects (p < 0.05). Carotenoids in CPC contributed to skin yellowness, which was significantly higher in the diet where 100% FM was replaced with CPC. Using regression analysis, the optimal substitution level of FM by CPC was estimated at 25% for percentage weight gain, 33% for FCR and 29% for protein efficiency ratio. CPC could be used as a single plant protein source to substitute up to 50% FM in red hybrid tilapia diets.

The objective of this study was to investigate the potential of enhancing the dietary substitution of fishmeal (FM) with corn protein concentrate (CPC) in the diets of red hybrid tilapia, Oreochromis sp., by blending CPC with soy protein concentrate (SPC) and adding betaine‐HCl and dried basil leaves (DBL; feeding attractants). Seven isonitrogenous diets [FM100‐CPC0‐SPC0 (control); FM25‐CPC75‐SPC0 (75% of FM replaced by CPC); FM25‐CPC50‐SPC25 (50% and 25% of FM replaced by CPC and SPC, respectively); FM25‐CPC50‐SPC25B (with 0.5% betaine and 2% DBL); FM0‐CPC100‐SPC0 (100% diet protein from CPC); FM0‐CPC75‐SPC25 (75% and 25% of FM replaced by CPC and SPC, respectively) and FM0‐CPC75‐SPC25B (with 0.5% betaine and 2% DBL)] were formulated. Triplicate groups of tilapia fingerlings (average initial weight, 7.31 ± 0.03 g) were fed one of the diets for 56 days. The effects of high dietary levels of plant protein concentrate (PPC) on growth, nutrient utilization, body composition, body colouration and gut histology of tilapia were investigated. High levels of dietary CPC significantly (p < 0.05) reduced fish growth and feed intake. Blending CPC with SPC restored the growth performance of tilapia at the 75% PPC inclusion level. The addition of palatability enhancers further improved the growth of tilapia fed high PPC‐based diets.