A study was conducted to examine the effect of dietary cation-anion difference (CAD, Na++K+-Cl−, mEq kg −1) on acid-base balance, food consumption and growth of juvenile African catfish, Clarias gariepinus. Four dietary CAD levels (-100, 100, 500, 700 mEq kg−1) were established by altering levels of NaHCO3,CaCl2and NH4Cl in the diets. The group fed the diet of excess anions (CAD: -100 mEq kg−1) had low food consumption and growth rate. Food consumption and growth increased linearly with an increase in dietary CAD within the range -100 to 700 meq. kg−1. Blood pH was not significantly influenced by dietary CAD. A quadratic relationship between Na+, Cl−and CAD level in plasma and dietary CAD was found. Body composition of fish and nitrogen/energy utilisation efficiency differed between dietary CAD treatments. The results suggest that dietary CAD influence acid-base regulation and thus the energy costs for maintaining homeostasis. The increased food intake and growth performance of C. gariepinus at higher CAD levels may be related to a reduced maintenance costs for homeostasis.