The possibility of replacing fish meal with fermented soy pulp on the growth performance, blood biochemistry, liver, and intestinal morphology of African catfish (Clarias gariepinus)

The development of plant ingredients as an alternative to fish meal (FM) has received sustained interest in the aquaculture sector. The study investigated the replacement of FM with different percentages of dietary fermented soy pulp (FSP) to assess the growth performance, haematology, blood biochemical, liver, and gut morphology of African catfish. Five isonitrogenous (32 % crude protein) diets were prepared with FSP by replacing 0 % FSP (D1), 25 % FSP (D2), 50 % FSP (D3), 75 % FSP (D4) and 100 % FSP (D5) of FM component of the diets. The results showed a significant difference (p < 0.05) in growth parameters where the fish fed D3 diet showed the highest weight gain, specific growth rate, and condition factor compared with other diets. The mean values of Red Blood Cell (RBC) and Lymphocytosis (LYM) were significantly highest (p < 0.05) in fish fed the D3 diet. The albumin (ALB), globulin (GLOB), and total protein (TP) were significantly lower (p < 0.05) in the control diet compared with the experimental diets. In addition, the D3 diet provides the highest total lactic bacteria (LAB) and total bacteria (TB) compared with other diets. FSP as a protein replacement of the FM had a significant effect (p < 0.05) on villus length, width, and crypt depth in fish's anterior and posterior gut. The histological study of the intestinal revealed that the gut of the D3 diet had an intact epithelial barrier with goblet cells arrangement and very well-organized villus structure, tunica muscularis compared with the other treatments. In conclusion, the replacement of 50 % FM with FSP could be used in the aquafeed industry for better growth and health status of African catfish and possibly for freshwater species.