Nile tilapia Oreochromis niloticus is one the most farmed fish species in the country and it has been globally traded fish food around the world. This is because tilapia has positive aquaculture characteristics such as fast-growing fish, high-market demand, excessive breeding and minimal environmental requirements. Commercial approaches were used to control the spread fish diseases in various aquaculture farms, such as the use of anti-microbial agents and vaccination, but they have limited success in the prevention of/or treatment of aquatic diseases. Thus, the present study was conducted to evaluate the growth performance, immune response and disease resistance of Nile tilapia Oreochromis niloticus fed diet with different levels of Amaranthus spinosus leaf meal (ASLM) following Aeromonas hydrophila infection.
Fish were fed with a diet containing 25% (ASLM), 50% (ASLM) and 75% (ASLM) replacement of fish meal by ASLM. Formulated diet without ASLM served as the control (C). At the end of the experiment, growth, haematological profile and disease resistance to A. hydrophila infection of fish were evaluated. The influence of ASLM on the immunomodulation in O. niloticus was observed by evaluating its survival after A. hydrophila infection. Based on the results, the final weight, weight gain, daily growth rate and feed conversion ratio were significantly increased in the fish fed diet with ASLM50. The results also revealed that red blood cells (RBC), hemoglobin (HGB), hematocrit (HCT) count of fish fed with ASLM50 and ASLM75 were significantly higher than that of fish fed with C and ASLM25 before and after bacterial challenge test. However, HCT count of fish was comparable among treatments. The percentage survival of fish fed diet with ASLM was higher than that of C. Overall, replacing fish meal at 50% ASLM is promising in enhancing the fish growth performance, haematological profile and resistance to A. hydrophila infection.