Fishmeal (FM) is one of the major protein sources used in fish diets, which was obtained from wild fish catches. Due to the steady decline in fish catches accompanied with the increased demands for aquafeeds, a rapid decrease in the FM availability is much more expected. Alternative protein sources of animal origins, such as dried black soldier fly (Hermetia illucens L.) larvae meal (DBSFLM), may be used as an alternative protein source instead of FM in aquafeeds. Therefore, a feeding trial was carried out to evaluate the effects of partial replacement of FM with DBSFLM on growth performance and body composition of European sea bass, Dicentrarchus labrax. A basal diet (45% crude protein) was formulated, where DBSFLM protein replaced 25, 35, or 50% of FM protein. Fish (12.1 ± 0.21 g) were fed one of the tested diets up to apparent satiation thrice a day for 8 weeks. No significant differences were observed in fish growth, feed utilization, and survival (P >.05). The DBSFLM inclusion in diets of European sea bass did not affect its body constituents. Additionally, values of red blood cells, hemoglobin, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were not significantly influenced by DBSFLM inclusion in fish diets as compared to the FM-control fish. Likewise, no significant changes were observed in counts of white blood cells, lymphocytes, monocytes, and neutrophils in DBSFLM-fed fish as compared to the FM-control fish. The DBSFLM inclusion in diets for European sea bass did not affect levels of serum total protein, albumin, globulin, serum alanine aminotransferase, and aspartate aminotransferase. The simple economic analysis evoked that feed cost decreased with increasing DBSFLM levels in fish diets. The findings of the present study elucidated that the growth performance was not significantly changed by partial replacement of FM protein up to 50% by DBSFLM protein, which reduced the feeding cost by 15.6% as compared with the FM-control diet.
