Replacement of Fish Meal by Black Soldier Fly (Hermetia illucens) Larvae Meal: Effects on Growth, Haematology, and Skin Mucus Immunity of Nile Tilapia, Oreochromis niloticus

Simple Summary Fish meal (FM) is the primary ingredient of the farmed fish's diet. However, the decline in wild fish catches, and the growing demand for aquaculture feed have resulted in a dramatic reduction of FM supply. Thus, it is essential to seek for alternatives, such as insect meal (IM), to support sustainable aquafeed production. Among insects, the black soldier fly larvae are promising because they are rich in essential amino acids, minerals, and vitamins. Therefore, the present study was performed to assess the effects of IM as a partial or total replacement of FM on the growth and hematological parameters and skin mucus immunity of Nile tilapia. Growth and feed utilization efficiency indices, feed intake, survival rates, and hematological parameters were not significantly different between FM and IM fed fish, while the mucosal immune response was improved in IM fed fish. In conclusion, these results show that IM can be used to substitute FM in the Nile tilapia diet. These findings can be used to develop alternative aquafeed for sustainable aquaculture. Fish meal (FM) is no longer a sustainable source for the increasing aquaculture industry. Animal proteins from insects may be used as a FM alternative source as long as they do not create adverse effects in fish. Black soldier fly larvae meal (BSFLM) was tested in a 12-week experiment on Nile tilapia (Oreochromis niloticus). Four hundred and twenty (14.77 +/- 2.09 g) fish were divided into seven groups and were fed seven diets: control (0% BSFLM-100% FM), and FM replaced by BSFLM at rates of 10%, 20%, 40%, 60%, 80% and 100%. Growth indexes, feed utilization efficiency indices, feed intake, and survival rate were not significantly different (p > 0.05) between FM and BSFLM fed fish. Values of red blood cell, white blood cells, hemoglobin, hematocrit, mean corpuscular volume and hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, and platelet values were not affected by BSFLM. Skin, mucus lysozyme, and peroxidase activities were improved in BSFLM fed fish. BSFLM can be used as a substitution for FM in the Nile tilapia (O. niloticus) diet at up to a 100% rate with no adverse effects.