In present study, maximum value of Relative gut mass (R.G.M.) was perceived in T₃ while least relative gut mass (RGM) was observed in T₄ (0.039±0.0005). Highest mean value of Relative gut length (RGL) was observed as 1.45±0.05 in T₃ and minimum (RGL) was determined as 1.22±0.03 in T₆. Least value of Zihler’s index was observed in T₄ as 0.023±0.002 (p>0.01) while maximum Zihler’s index as 0.08±0.01 in T₁ as a small fish exhibits large Zihler’s index. The increasing trend of digestive somatic index (DSI) was observed as T₃>T₂>T₆>T₁>T₅>T₄. Amylase secretion of Sperata seenghala reported significant discrimination with different crude protein (CP) showing prominent variations. Higher most Amylase action was determined in T₁ (30% CP) having 0.50±0.09 (U/ml. Min^-1) (p<0.001) as its mean value with range of 0.40-0.58. However minimum amylase activity was witnessed in T₆ and T₅ as 0.35 ± 0.7 and 0.38 ± 0.85 correspondingly. With increased crude proteins action of protease reported positive relation with various feeding groups. Lowest crude protein percentage in diet (30% CP) depicted lower most protease actions (1.48 ± 0.22) while higher crude protein T₅ (50% CP) and fish meal (T₆) displayed greater concentration as 5.71±0.33 and 5.07±0.24 respectively. All experimental groups reported highest lipase activity than other enzymes.