This work assesses the dietary use of two insect meals of Tenebrio molitor (TM) larvae reared in conventional (TM-10) or MAPs-enriched substrates (MAP-TM-10) as fish meal replacements (10%) in the diets of gilthead seabream (Sparus aurata). Fish (n=4,500; 207.19 ± 1.47 g) were divided into three groups with triplicates: Control (fed conventional diet), TM-10 and MAP-TM-10 groups.The fish were reared in floating cages for 12 weeks and The dietary effects on white blood cell ac-tivation, heat shock proteins, MAPKs, and apoptosis of the fish were evaluated. The MAP-TM-10 group exhibited the highest eosinophilic induction and plasma cells. Phosphorylated levels of p38 MAPK; p44/42 MAPK; HSP70 and HSP90 increased in the TM-10 and MAP-TM-10. In terms of apoptosis, Bax levels were lower in the TM groups compared to the Control, and the MAP-TM-10 group showed even lower levels than the TM-10 group. Bcl-2 levels increased in the TM-10 compared to the Control, and further increased in the MAP-TM-10 group. The Bax/Bcl-2 ratio, an apoptosis indicator, decreased in the TM groups, with the MAP-TM-10 group showing a further decrease compared to TM-10. These findings suggest that insects breeding substrate enriched with MAPs modulated the effect of TM on cellular stress and apoptosis.