“…Also, endogenous enzymes (e.g., proteases existing in fish) continue enzymatic hydrolysis of proteins or exogenous enzymes in order to promote the hydrolytic process, so the molecular size and hydrophobicity of the hydrolysate were strongly influenced (Batista, Ramos, Coutinho, Bandarra, & Nunes, ). The protein availability and subsequent digestibility increased because of small polypeptide chains or short chains of amino acids that produced during the hydrolytic process (Silva, Rocha, Moreira, Signor, & Boscolo, ). Siddik, Howieson, Partridge, Fotedar, and Gholipourkanani () observed increased micromorphology of intestinal parameters such as fold height (hF), microvillous height (hMV) and external circumference of serosa (ECS) with the inclusion of PH in diets which could enhance growth performance of fish through increased nutrient uptake in more surface area, but Cahu, ZamboninoInfante, Quazuguel, and Gall () suggested the saturation of intestinal transport mechanisms by high luminal peptides and amino acids as a possible reason for inferior growth in some species.…”