A 16-week experiment was conducted to assess whether dietary supplementation with Digestarom® as a phytogenic feed additive could reverse the negative influences of high stocking density in Nile tilapia (Oreochromis niloticus). For this purpose, 240 fish (2.4 ± 0.1 g) were divided into six groups. Two groups (D1 and D2) were fed a basal diet and reared under different stocking densities of 125 and 250 fish per m3. The other fish groups (D3, D4, D5 and D6) were raised under a high stocking density of 250 fish per m3 and fed supplemented diets with Digestarom® P.E.P. MGE at levels 50, 100, 200 and 300 mg per kg diet respectively. Growth retardation and impaired feed efficiency resulting from rearing fish at high stocking density were improved in groups fed diets fortified with 200 and 300 mg Digestarom® per kg diet. Moreover, rearing fish at a density of 250 fish per m3 significantly reduced Hb, RBCs, MCV and total protein but increased WBC, MCHC creatinine, urea-N, ALT and AST. On the contrary, enriched tilapia diets with 200 or 300 mg Digestarom® per kg diet significantly corrected the earlier altered haematological indices and serum biochemical indicators. Furthermore, the addition of 300 mg Digestarom® to the diets of tilapia reared at high stocking density significantly modulated lipid deposition and ash level in their flesh. Conclusively, supplementing the Nile tilapia diet with 300 mg Digestarom® per kg feed could be a promising supplement for combating the negative impacts of high stocking density.